Episode 149: Lighting Cannabis Right: 2025 Science & Strategy with MIGRO

Welcome to the Cannabis Cultivation and Science Podcast. I'm your host Tad Hussey of KISS Organics. This is the podcast where we discuss the cutting edge of growing from a science based perspective and draw on top experts from around the industry to share their wisdom and knowledge. Before starting the podcast, I wanted to remind folks about the Cannabis Cultivation and Science conference that we are hosting in conjunction with Collective elevation in Bozeman, Montana. The event is happening on September 5th through the 7th this year. Early bird tickets are still available and it's going to be an amazing three days of networking the latest in cannabis research and innovation and culminating with a tasting event hosted by the Montana Living Soil alliance that's included in the price of the ticket. Now my podcast this week is all about lighting and photobiology. My guest is Shane Torpy. Shane is the founder of Migro, a grow lighting company. He has a background in manufacturing, engineering and construction. He turned his hobby growing into a new business and established Migro in 2016. Alongside selling grow lights across the world, Migro also has a grow lighting channel on social media. The channel hopes to educate and help growers reach their potential by featuring the latest science and technology in grow lighting. Now onto the show. Hey Shane, thanks for coming on the podcast today.

It's a pleasure, Todd, thanks for having me on.

Yeah, I'm really excited to talk to you about lighting. I've been following you guys for a long time now and everything you've been doing with your lighting reviews and I'm excited to hear from you sort of. What do you think the lighting Trends are in 2025? Where are we headed for indoor lighting?

Yeah, so suppose just you know, in recent, in the recent past the trends have been to increase power intensity. So with the use of LEDs, it allow it's the output less heat basically and they're a lot more flexible than HPs were in the past. And what people are doing is just pushing it harder. So increasing the power intensity where previously, you know, 10 years ago we would have been operating at about 500 par. 500 micromoles per meter square per second. That would have been, you know, the equivalent of a, say a 600 watt HPS in a 4 by 4 space. Whereas now certainly commercial growers are up around the sort of 1300 micromoles. So pretty much three times the power intensity than you know, ten years ago. And even on the home grower front similar most grow lighting companies would be recommending now about 900 to 1000. So that's really great for the grower because you're getting twice the yield from the same space, two or three times the yield from the same space than you were five or 10 years ago. There are also developments with regard to spectrum. So now I'm not convinced and we'll get into it later about whether these are all beneficial. But there are certainly a lot of companies which are adding UVA and far red LEDs to extend the, what is the regular power spectrum. So previously it was thought that plants were only. Our photosynthesis was only driven by frequencies of light. And that's basically colors of light from 400 to 700 nanometers and that's from sort of deep blue up to deep red. And there's been more experimentation done the last few years to show that UVA is also photosynthetic. So as you just creep down from that blue into the UVA region. And there's been a lot of studies published on the benefits or otherwise of that. And then there's also quite a lot of experimentation and studies that have been released around far red. So looking at extending that spectrum beyond 700 nanometers into far red, it's not yet infrared, which is heat radiation, it's before that. But that is also being proven to be photosynthetic. So it causes growth, but it can also change the morphology or the shape of a plant, the way the plant grows. And so there's been quite a lot of experimentation with, you know, because we have LEDs and we can, we can change spectrum around, take bits in, take bits out and do sort of side by side or control tests. People have been studying those aspects a lot more and releasing quite a lot of papers on them, multiple papers from around the world which are demonstrating, you know, the benefits or otherwise of this spectrum. Outside of that, I'd say really it's probably more about controls. I think that's the other factor that has come in the last few years. So a lot more growers, in particular home growers, are using controller technology. They're hooking up their grow space with, you know, a little computer controller which were very expensive. Again, 10 years ago. You could be $500 for a little basic controller with a few buttons on the front. And now you're getting a all singing, all dancing, complicated, complex controller that you can use remotely and monitor remotely and hook up all sorts of different types of equipment. So I think there are probably the three areas that I see a lot of development in, in the lighting space at the moment.

Yeah, I want to stay fairly brand agnostic in this podcast because I think people lighting is a little bit of a hot topic in that people will have their favorite, just like they have their favorite way of cultivation and that can get a little, a little heated for folks. That being said on the controller side, can you maybe plug some names or some reviews that you did that might, that someone who was looking for affordable home controller they might want to consider?

Yeah, so probably two of the biggest ones or the most popular ones around at the moment are vivosun and AC Infinity. So both of those companies do a broad suite of indoor gardening products. So they do everything from the lighting to the controllers to the fans to the pumps, air conditioners, all that sort of stuff. This is mainly home growing. At the home growing end they're probably two of the biggest ones and I've worked, I get a lot of queries and questions from, from customers about okay, does it work with that and can I hook up with this? And a lot of them are related to AC Infinity so they don't seem to be doing a large volume of business. Some of the others, Mars Hydro, Spider Farmer, they have their own proprietary systems although they don't seem to be as open to integrating with you know, outside or other brands equipment. And then you kind of get into the more commercial type controllers like Trollmaster. But they would be multiples of the prices of these AC Infinity controllers. Like to buy these little controllers now, you know, they've got the little display screen inputs and outputs. They come with their thermometer and moisture sensor or humidity sensor I should say. And they are like $60. Wow.

Okay. Very affordable.

Very, very affordable. And you know, for, for the grower to be able to control, you know, the airflow through the tent based on the humidity levels and the temperature. That to me is the most critical part. To be able to do that with their extract fans and keep the grow within a defined set of parameters in terms of, of temperature and humidity is a real boost to, you know, the productivity you're going to get to the growth rate and also the quality at the other end. So yeah, it's, it's a, it's a really inexpensive way to improve and plus you get the monitoring too. So you know, if you do make an error or something happens, you can look back, you can see, you know, oh, the temperature spiked or whatever happened and you know, learn for the future. So yeah, incredible breakthrough. Really? Yeah.

That's amazing. I haven't dove too far onto the controller side. I've traditionally just use a light timer and then I have a, you know, a basic Controller for my fans that would be set on a sensor for humidity or, or things like that. But the idea of having sort of a master controller would really simplify all of that. It makes a lot of sense at that price point for I think everybody.

Oh, absolutely, absolutely. Yeah.

Very cool. Well, I know we talked a little bit about. You mentioned Spectrum and you talked about some of the research that's come out around it. You know, I think back to or originally when LEDs first came out. I know for years we were saying, you know, they're not quite there yet. You know, as an HPS grower in terms of making that switch, we had this blurple color and, you know, we used to think that green light wasn't photosynthetic. And so we could have green light in our grow or turn on green lights to go work in there during the dark cycle. As you stated, we kind of learned that these, you know, we've evolved as an industry and learned that these things are not optimal. What, what are your thoughts on the direction? Because I've seen as a trend with the, the lighting companies, I work with a higher edition of red in the more recent iterations of lights. I can't speak to far red, but definitely more, more red, that warmer color tone. I think with the idea of mimicking a little more of what we're getting from HPS on in terms of a spectral intensity or a spectral range. What, what are you seeing or what are your thoughts on all this?

Okay, so let's look at the recipe. What we want first of all. So plants, they grow out in the sun, they get pretty much a straight line across. If you look at all the wavelengths, a straight line across. There's loads of red, there's loads of green, there's loads of blue. It's just packed out. So the sun spectrum is just. You get everything as we know, and you get that lovely, clear, crisp, white light. Hps, if you looked at it, it would be a chart that would look like this. It goes up and down. It has different. It has a spike of green, a spike of yellow, a spike of green, a spike then of orange and red. So it's pretty all over the place. One of the biggest downsides with it was it didn't have very much blue. And plants respond to blue. If there's not enough blue in the spectrum, they stretch. So we need a sufficient amount of blue, about 5% blue, 5, 6% blue, in order to have short, dense plants, which is what we want because we're in a tent and we don't want the plants, you know, growing everywhere. So that, that was a big development, is getting away from, you know, having to use metal halide in veg and HPS in flower. So we could use one light then. So we started calling that full spectrum because it's got, you know, white light. You know, white light is made up of blue, green and red mixed together. So white LED lights, when they finally came out, I suppose we're talking 10 years ago now, they were considered full spectrum and that was it. Like, why would you want anything else? You've got everything. And that was true to an extent, but we had other things to play with. So people wanted to mess around and see what they could do and experiment and test, which is great. One of the things was efficiency. And you're talking about those little red diodes that you'd find on a modern grow light. They're actually not. So people put two and two together and thought that was for flowering, because, you know, HPS would have been sort of more red and orange for flowering. But it's not the case. The plants will more or less absorb all of those photons equally. Right? Blue a little bit less than green, green a little bit less than red. So red is the most photosynthetically efficient. It'll be absorbed at a higher rate by the plants. But the most important thing is it's electrically efficient. So if I consume a watt of electricity with just white LEDs, I'll put out, say, one unit of power. If I consume a watt of electricity with these red, deep red diodes, they're called 660 nanometer diodes, they'll output nearly twice as high a rate of power, so nearly two units of power. So electrically they're more efficient. So if I have. I describe it a bit like being a turbo booster on an ice or combustion engine, that you're adding these red LEDs to the white LEDs in order to boost your efficiency, the whole system. Efficiency increases by halving them in it. Nothing to do with promoting flowering or you don't get better flowers and more red or anything like that. Now, that's a chase for efficiency, and that's great. There is a downside, and you have to be careful that if you have too much red as a proportion, particularly at the higher intensities, you can get light bleaching. So not burn, just bleaching. I've looked at this, I've read about it. I still don't understand the mechanism. It's very complicated with photosynthesis, but basically it turns the chlorophyll, it bleaches the chlorophyll and it stops being green. So we don't want too much red in there, but we want as much as we can get away with because it's more efficient and it'll reduce the running cost of our, of our lights.

So another way of putting this, and correct me if I'm wrong, is you're saying what we're getting with these lights that have a little more red is, and efficiency is I can use less electricity to receive more photosynthetic light. How does that come into play then in terms of the amount of heat that's generated? Because I've, I've always thought of efficiency, like especially with LEDs, is they put more, more of that electricity, that electric energy into photons versus putting it into radiant heat like that, you know, old fashioned HPS ballast, you know, and light would get really, really hot. So we, yeah, we'd have to have cooling in the room and all these other things. With LEDs, we're actually doing the opposite. We're having to add heat sometimes in, in certain cases. And it's a completely different beast altogether. What's, what's really going on there.

So the more efficient your fixture is, the less energy is going to be wasted as heat. So, and that's just not so. Typically you measure a light fixture, you put into this thing called an integrated sphere, which is a sphere. You put the light fixture in, you power it up and it measures the total output. So all the light output from that light fixture, and if you put in a bulb, HPS bulb, for example, it's going to radiate out in all directions and you'll get a certain efficiency for that bulb or that LED chip. But more than that, when you put that into a grow situation, for example, you want that light directed in one direction basically down onto your plant canopy. You don't want shining up at the ceiling, and some of it you'll be redirecting down with reflective material at the sides. You know, if it's in a grow tent, you get a lot of what's called reflectance losses then as well. So if you shine light against a reflective wall, say it's Mylar wool, about 94% of that will come back. Say for argument's sake, between 90 and 95% will come back. The 5% that's lost is absorbed by that material and generates heat. So you have this electrical efficiency. So the efficiency of your bulb, the more efficient your bulb is, the less heat will be will be wasted. So for every watt consumed, for example, with a HPS bulb, you're emitting about your 30% light and about 70% of that is heat. With a, with the modern LED system, it's almost flipped, so it's about 40% heat waste and about 60% light. And what that means is if you want to get, if you do a comparison grow, for example, and you wanted to get the same yield from two separate spaces with an old HPS bulb, you would need about two and a half times as much wattage to achieve the same growth. And a lot of that extra wattage is waste, and nearly all of it is waste. So you can reduce heat output or heat in the grow area by about 70% from going, for example, from HPS to LED within LED. Then, you know, with modern LEDs, most LEDs on the market today are at a base level. I'm going to talk about it as a system efficiency, but probably at about 2.3 PPFD per watt, that means there's 2.3 par for every watt consumed. A very good one would be about 3, so about 30% better. That's about the range. So with a relatively inexpensive LED to a very expensive one, you'll get about a 30% reduction in consumed power and heat.

And that's massive on a commercial scale. You know, when you're using a lot of energy, that's.

Yeah.

And when you mentioned the heat with hps, that brought me back to my, you know, initial growing days. And in a tent, you know, someone said, go ahead and try two 600 watt HPS lights, you know, air cooled at the time in a tent. And I had that with an 8 inch fan going full speed and I still, I could not control the heat. So the heat was the limiting factor.

Yeah.

For me in a tent space. So LEDs would be, would have been a game changer, you know, 15, 20 years ago when I was doing this. Yeah. So I think that's, I think that's one thing for tent growers to keep in mind too, if you're making a decision. I mean, I don't know if people are even still considering HPS all that frequently, but that heat is a big issue in small spaces.

Yeah. So with the spectrum, we've got these LEDs now, these white LEDs, we supplement with the red. We do that for efficiency. It's nothing to do with the spectrum per se that we're trying to affect the plant in any particular way. They're fine. And there's lots of variations of that. And people will look at these spectrum charts and they'll look at the, the angle of this part of the curve and stuff and they'll dissect it like this. I've seen very, very little evidence, almost no evidence that changes in the spectrum, in that power spectrum will have significant effects on yield or quality of yield. Very little evidence. So we were talking off air about Bruce Bopey earlier on. They're doing studies in, in universities with sophisticated equipment, with very sophisticated controlled experiments. And they did it with for example, LEDs of different color temperature. So you know, running from 2K or very warm white up to 5K or very cool white, so varying the proportion of blue and red etc. And they found negligible difference. So not a statistically significant difference between them in both yield and in quality. So you know, flavonoids, terpenes, cannabinoids, etc. Now I've said that 100 times, but, and there's evidence there, but unfortunately, due to, you know, a lot of the marketing that goes on around the place, people will promote their spectrum as being this spectrum or the that spectrum. And we've got the special recipe. It's complete nonsense. And not only that, there are going to be marginal gains you can get with different strains. So for example, you might have a strain that's very prone to stretching and in a commercial environment you may decide to use a spectrum which has very high proportion of blue, so it promotes very short and dense growth in order to deal with that particular strain and control it in a particular way and get, you know, single digit percentage margin improvements in your yield or in your whatever. But most home growers are growing different strains and going from one to the other and they don't know which lighting recipe is going to optimize that, that few percent. So for most people it doesn't matter because if they had a variable spectrum light, they would know what to do with it because there's no information out there telling them for the strain that they're growing or for the particular plant they're growing what is the optimum spectrum for them. Additionally, there's been playing around with UVA LEDs because they exist. We stick them on the lights and we're, we're saying we want to replicate the sun spectrum more. And UVA has a bit of mysticism about it a bit. I think people are not quite sure what it is exactly and therefore maybe it does something that they're unaware of or haven't been made aware of. However, plants see it really mostly as Blue, So they don't really differentiate. The way we do that, once the wavelengths go from 400 nm nanometers to 399, that it has a totally different effect on the plant. It doesn't really. So the small amount of UVA LED UVA that's put in these fixtures is highly likely to do nothing special, but they're much more expensive to buy and install and they're more likely to fail. So they're an expensive addition for something that's never been proven. Similarly, far red on the other end, so that's beyond deep red. So there's LEDs available, pretty efficient ones at 730nm, and they have proven to be photosynthetic, but less photosynthetic than the red ones. So they're more expensive to buy. They'll produce less in terms of growth. Excessive use has been proven to cause stretching, so it actually does the opposite of blue. Too much far red. The plant perceives that it's in shade. So if you go under a tree, out under the sun, the far red actually penetrates the leaves and can come through. So you get a higher proportion of far red when you're in shade in nature. So the plants use it as a signal to say, stretch, get out of here. I want to get. I need to get to the light. I'm being overshadowed. Um, so. Yep.

Sorry. Isn't that part of the argument, though, of why people say you want to use far red, is because you're getting further canopy penetration, therefore better flower development further from the light?

You could make that argument, but. Yeah, you can make that argument. Yeah. But there's no evidence to support it. So the same argument is with green, by the way. So if you look at a cross section of a leaf. I have a few posts on my Instagram from a few years ago. Again, I borrowed the information from Bruce Bugby and his team and it's an incredible graphic image, but it's showing the cross section of a leaf and it looks at how deep, different spectrum penetrate into the leaf and red is absorbed very clear near the surface. Blue penetrates a little bit further and green goes much further again. Green and far red go much further again. So that whole plant photosynthesis, you know that your light is penetrating deeper down into the plant. If you've green in it, you know, the far red argument is null and void. It's redundant. But it also. Also, there's been studies out in the last couple of years and these are published both in Canada, from a university in Canada Dutch University from Amsterdam, as well as some US ones. Now some of these are on medical strains, so it's CBD varieties. But it shouldn't make any difference in terms of, you know, the general, getting general learnings from it. But it has shown that far red above sort of 7, 8%, as you go up into those higher levels will actually affect your quality. So you'll get a reduced quality harvest as well. So like there's, I make LED lights, I sell them, I market them, all that stuff. I don't have UVA and I don't have far red red LEDs added. There's a little bit of far red comes from your white led. Anyway, you know, the spectrum isn't totally neat on a white LED. It doesn't just cut short at 700 nanometer, it goes up a little bit. So I tell people that just to sort of quieten them down or know, satisfy them for their far red craze, you know. But lots and lots of evidence showing UVA and far red does not make any difference and zero evidence that I've seen that it does make a difference. So, you know, I'm an engineer and a scientist and as great as it is to hear stories from people that I use this light and I'm the best grower ever and I, you know, I don't believe it unless there's evidence build up in control testing with reliable, with reliable testing and results. Yeah.

Yeah, I love that because it's tricky in cannabis because traditionally there hasn't been a lot of research in data so we've had to rely on our buddy that said, I started using, let's say this far red light and suddenly my plants did way better. So we think, oh, far red equals good. But now we do have access to research and data and I think marketing has gotten a little bit more insidious and a little bit harder to parse out what's actual research and data from what's marketing. And so I know you and I talked a little bit about this right before the podcast. I was talking about biomimicry and this idea that because the sun has far red, our lights need to have far red is, is not necessarily what's optimal or what's shown to be optimal from a plant growth perspective based on the research. And so I think if we want, if we want to follow the data and follow the research, then we really need to be willing and open minded to hear what it's saying. So what I'm hearing from you is there's, there's not a lot of. Right. Research around UVA and Far Red at this point that that would show its inclusion in a grow light is going to be beneficial for your plants.

Even stronger than, even stronger than that. I'd say there's lots of evidence to say that it isn't beneficial.

Okay, great, great. And then another way of saying this, again giving homage to Dr. Bugbee, is that light intensity. So your, your PAR level, your PPFD level plays a much more significant role in relation to yield than spectrum. And that still hasn't been disproven. Correct.

Correct.

Okay. And that, that, that came out a few years ago. So we've known this and I think that's really interesting. Now I did have some questions to follow that up. So we, we, you mentioned intensity. I want to talk a little bit about that sort of ppfd. So the amount of photons hitting a leaf surface, you know, you said we were at 500 to 700 back in the day. Now we might be 900 to all the way up to 1300. I've seen now. Sorry, I'm jumping around a little bit here. Dr. Bugby has shown that cannabis is a highlight plant similar to corn. We can push a lot of light at it and our yields will continue to increase. Yeah, with let's say most, most cultivars out there, we have to keep that into account. And, and I want to also preface this by saying as we raise light intensity, we are also, also adjusting the environmental controls VPD associated with that. So people, please keep that in mind if you're thinking about any of these experiments at home. That being said, I have a number in my head for living organic soil that I like that I think is high enough. What, what is sort of your level though first? And maybe we can have a little dialogue around this and maybe I can learn something as well. So what are your thoughts and does it vary based on cultivation method?

Okay, so just to give listeners a little bit of perspective first, so if I go out with. So we're talking about measuring par, photosynthetically active radiation. And we measure that at a particular point. If we measure, you know, what's the PAR hitting my hand in the sun, we call it ppfd, Photosynthetic Photon Flux Density. So the flow of photons onto my hands, how dense is it? And if I go out in the midday sun in July, it'll be 2000 or up to 2000, depending on where I am in the world. So that's what's available in nature. And obviously if that's what's out there. Plants can comfortably withstand 2,000 micromoles or 2,000 PPFD. However, plants have a limit the amount they can absorb over a given day. So when we're growing indoors, you know, we could target potentially 2,000 micromoles. But you would have a relatively short day because the plants wouldn't just wouldn't be able to absorb all that light. They have a limit to the amount that they can take up over a given day. Now traditionally we would have looked thought of like very light, hungry plants like say tomatoes or peppers or that sort of thing. And they would have required, here's another term I'm afraid called dli, the daily light integral. So the daily light integral. Integral means the sum of over the day. So the sum of light over the whole day. So for example, if I was growing at about, if I had about a PPFD of about 900 and I was growing for 12 hours as I would typically if I was flowering plants, that equates to approximately 40 DLI. Okay, Daily Light integral. And that's about what tomatoes would have been targeted. So if I had a greenhouse and I had supplemental lighting, I would be measuring the amount of sunlight that's coming in through the greenhouse and I would be supplementing that with artificial light to make about 40 DLI combined. And that would be maximizing the yield I can get from that crop over the life cycle of it. Now the variations that come in here are we don't just have 12 hour light cycles, we also have autoflowers. So people run them on 20 hour light cycles or even 24. We, we've got our vegetation cycle. So people probably running about 16 or 18 of our hours long for that. And then the last sort of category for me is very young plants. And I mean like seedlings and clowns that haven't fully properly rooted. And so I'll start with those. Typically say you have a lights on for about 12 hours per day. I would recommend only 2 or 300 micromols for young seedlings and cuttings who haven't fully rooted. And by that I mean, you know, if you're in a small pot, you start seeing a couple of hairs coming out the bottom of the pot or at the edges. Yep.

Can I, can I ask you a question about that? You said 12 hours with cannabis specifically or any plant that's photoperiodic. Don't we still need to have that longer day length?

That was, I missed, I miss, I misspoke. Actually you're correct. Sorry. So, so with the seedling, say we're, say we're, it's 16 hours. But the reason I would have a lower light intensity is just purely that I don't stress them too much. If their roots haven't developed that they can. If the roots are developed, they'll be able to uptake the water and nutrients they need to support the growth that's being demanded of them with the light. And so I caveat everything with just be careful of your young little baby plants and be gentle with them. Next though, once you get sort of probably three to four weeks in, you're starting to see, you've seen branching, maybe three or four branches coming out. You're probably 6 inches high at this point. You've put them into a pot that's, you know, a significant, you know, at least a pint pot sort of thing. You can then get it up very sharply. And again, this is Bruce Brugby's guidance because they've done this. But you can ramp it right up even in that long light cycle stage of 18 hours, you can ramp that up to that sort of 6, 700 micromoles, even up to 900 through that veg cycle on that long day. Now you're putting a lot of demand on the plant doing that. I wouldn't recommend it for everybody. In fact, I'm trying to sort of divide out growers as they come to my website to buy lights. And the best term I can come up with is home grower and pro grower. And you know, what I'm trying to say by that is there's some people will have their environment optimized, they're right on point with their medium and their nutrients, their genetics, everything else. And they're not going to have a bottleneck elsewhere if they put a large demand on their plants in terms of light intensity. So in short, for veg, I would probably recommend about 500 micromoles for a home grower and probably about 7 or 800 micromols for a pro grower, a very experienced grower. Now that's at an 18 hour light cycle. So we dropped to a two, a 12 hour light cycle.

Can I, can I ask you a couple questions while we're still in veg here?

Yeah.

So first of all, I just want to preface this by saying that all of Dr. Bugbee's research is done in a growth chamber, which is a very different environment than what we're dealing with as a grower, let's say, even with our most out environments. And he's probably doing it with, you know, a limited number of plants that he's really babying. So I tend to take his numbers and then drop them to account for the fact that I'm probably going to have more environmental stress than he is, based on his research.

Yeah.

Also, one other thing in the veg section I just want to throw out there is I tend to target, you know, around 600 PPFD. But that's saying, you know, like, even if you're a pro grower, my thing would be, like, based on your definition, I would just start my plants a week earlier. So I don't have, you know, I have. I'd rather extend my veg time based on when I need my next flowering crop, then try to ramp up too quickly and deal with the potential ramifications of doing it too fast. So I just want to throw that out there as another option for folks.

And I think I'd caveat anything I'm saying, tab by saying whenever I increase my light intensity, I go back and check for at least a day or two regularly to look for signs of stress. So, you know, a lot of things are strain dependent. So different strains will have different tolerance for light and be able to absorb. And as you say, depending on the medium and your setup and your environmental conditions, you may be stressing the plants too far and you may overstress them and cause problems and stunt their growth. So I would be. I would always say go as hard as you can, but be careful, you know, so, yeah, and listen to what you're seeing. You know, respond to what you're seeing. Don't just force it. So if you're starting to see stuff droop, particularly towards the end of a light cycle, your plants are probably overstressed and you need to reduce down that intensity or look at some other factors.

So my question that I went off on a tangent, but my question was how you mentioned ramping up. So let's say I'm at 200ppfd with these little seedlings now. My plant's gotten bigger. I'm ready to go up to 600. And you said you could do that in that day length. Am I going straight from 200 to 600 or am I going 200 to 400? Coming back midway through the day and.

Going, I'd probably do it in two steps over, over three or four days myself.

Okay, so. So you're saying ramp up relatively slowly over a few days is optimal. Okay, yeah, great.

Yeah. Having said that, you know, if it was just myself and my own I probably would just throw it straight up there and then just go back and check, but that's me. So, you know, it depends on your character whether you, you want to throw a little bit of caution to the wind, wind or not. But in that veg stage then. So say you're talking about your 600 number. Okay, so 600 in veg being if you change that from an 18 hour light cycle to a 12 hour light cycle, you're going to drop the total amount of light the plant is receiving by about a third. So you're dropping, so you need to, to increase that power intensity when you flip into flower just to stay where you are in terms of light intensity. So you need to increase your power intensity by 50% when you drop your, your number of hours. So you need to go from 600 to 900 micromols just to stay, you know, give the light, give the plant the same amount of light over a day cycle. Now that's, that's what I would recommend for most people is around 900. I think that's a, it's a good intensity. You're going to get a good growth rate. You're not going to overstress your plants. However, there's a lot of people. So it from a commercial perspective they're up around 1400. That would be standard specification, would be 1400 PPFT. Home growers can do it too. But I would caution and I think people who want to go that high probably know that they need to be careful too. So for example, at around 1200 micromoles or there about 1200 par, that's when you are going to, you know, with certain strains, with certain genetics, you're going to start to see problems occurring. So certain strains are less robust, less able to take that high power light intensity and they could, you know, foxtail, you could get some re vegging and you know, just, just generally affect the performance of the plant. You're going to reduce your yield and they're not going to grow from, from the stress. But I think that's it's, it's relatively few. It's a small, relatively small percentage, but it can happen.

So just to clarify, certain cultivars at higher light intensity will actually reduce yield because of the stress caused by the high light. That's really fascinating because the under the understanding in the industry is that more light equals more yield. And the research that Dr. Bugbee did showed this. But I want to highlight it wasn't a linear relationship. It's not a straight line.

Yeah, I would be Careful with that as well, because sometimes they weren't always showing the whole plant grown over whole light cycle under that power intensity. Some of those studies are putting them into a chamber and measuring photosynthesis. So they're measuring respiration of the plant, you know, so how much CO2 it absorbs and how much oxygen it expires. So some of those studies are instantaneous measurements. So I put the plant in, I put it up to 2,000 micromoles and it was photosynthesizing at a higher rate. But it may not. It doesn't mean that you can take that plant, put it under 2000 micromoles consistently for 12 hours a day for the next 60 days, and it will be okay. Now, there's a little bit of counterintuitiveness here. So as we're saying, you know, all these plants were, were, you know, developed over time under the sunlight, which is 2,000 micromoles in midday. Yes, but it's not all the time. It's not every day, and it's not all year. So, you know, and, and by the way, I've seen plenty of plants get stressed. So I live in Ireland. It's a relatively cool climate. We don't get huge amounts of sunshine. But if we get, you know, our very rare heat wave or clear period, you know, I see plants that are normalized to our environment but still get stressed by the sun in the middle of the summer. So, you know, it's.

Isn't that because they haven't developed that cuticle layer on the leaf to protect them from the higher light?

Because I, I'm not going to pretend to know. I'm not going to pretend to know yet.

That's how I, I remember it being explained to me from lectures, but it was quite a while ago.

But, you know, it makes sense though, if you have a root structure, for example, that is a certain size, and even if it's in a pot and it's limited and you're, you know, it has the same access to water every day that it did, you know, consistently, or the same moisture in the soil, for example, and you shine light on it and put a demand on that plant to respire, for example. So by shining light on it, it's trying to. It's photosynthesizing, but it's also respiring. So it's looking to take up water and evaporate it off the leaves as part of the process. If it can't get more water, it's going to be stressed. And because the sun is shining, but it doesn't mean it's getting more water because the sun is shining stronger. So like you were saying earlier on about the medium being a restricting factor sometimes in these cases I tend to agree with you that, you know, I think in hydroponics it's relatively easy to ensure that that plant never is deficient in anything because you can be very precise and very consistent with basically food and water for the plant and temperature. Whereas with the home grower at the higher light intensities with mixed medium. So, you know, whether it's with organic soil or, you know, cocoa feeding or whatever the case may be, I'm not as convinced that most growers can tune that well to ensure that they don't end up with deficiencies and stress related issues.

Yeah, in my own experience with light intensity, I did get some light bleaching when I was pushing 12, 1300 PPFD on certain cultivars on the buds that were higher. Because that's the other thing here. We're talking about light intensity of canopy. But canopy is not, you know, even the best grower is going to have some variability in their canopy. Some buds are going to be higher, some are going to be lower. Buds towards the edges of the margins of the light are going to be much lower PPFD than ones in the middle. And that's just the reality of, of a grow light.

That's physics.

So. Yeah, yeah. So I think knowing all that, you know, we're saying average, your average PPFDA canopy is sort of what I target. And so some, some of my buds have gotten much higher light and they definitely didn't develop quite as optimally, but I would kind of sacrifice those for the sake of the entire canopy.

What I often say to people, if you're not burning the tips of your plants, you're not going hard enough. You know, you, you that, you know, it's a sign, it's a measurement tool in a way. You know, that you can detect whether you're pushing it to the limit by getting a little, doing a little bit of damage to the tips of your buds. And you know, that just gives you a benchmark, really.

Yeah. Now you threw out some numbers. I've always established my flower numbers based around whether or not you're supplementing. CO2 is sort of the, the benchmark for that. And so like I've typically said, if you're not doing CO2, 800 PPFD is probably sufficient, maybe 900. But you're gonna, there's gonna be periods of time in your grow where you're gonna be below ambient just because the plants are working so hard. Unless you're really moving air through that room quite efficiently or that tent, let's say. Yeah, with CO2, I think a thousand eleven hundred. I think those were good numbers that you threw out there. And based on the research I've seen, and maybe, and I'm sure you've seen more lighting research than I have, that's sort of the sweet intersection between cost of electrical, of electricity in terms of the watts we're using and yield. Yes, we can go higher, but we're going to have to use a lot more electricity to get much smaller increases in yield as we move further to the right there.

Yeah. So being just with CO2, so, you know, we bring fresh air into, into the grow space. We're bringing in CO2 to feed the plant to help the plant respire. You don't have to supplement with CO2. So I have tested some of these things by the way, and the CO2 generators, you know, the mushroom stuff and the, you know, they don't really work. The only one that really works first of all actually to start at the start is you have to have a sealed grow room. So basically you have to have an air conditioned, climate controlled space. Because even if you use CO2 canisters, if you're having to evacuate, you know, heat and moisture outside and bring fresh air in, you're diluting that CO2 and it's pretty pointless exercise. So most, the bulk of home growers are not able to do climate control or seal their grow room. And Therefore supplementing with CO2 is not a reality, it's not a possibility at all. But when I talk, you don't have to have elevated levels of CO2 in order to utilize that higher light intensity, you know, to get up into that 12, 1300 micromoles, you don't have to. Certainly helps. But what does become an issue is even if you have say a 5x5 grow tent and typically somebody's got a, you know, they'll have a couple of passive inlets lower down the tent and they'll have the fan up high sucking air out from the top of the tent. Well, if you looked at, if you could see the air flowing through that tent, the air would be taking a lot of shortcuts. You know, the air is not going to come in through a passive vent down this side and sort of go over here to make sure it goes through all of that canopy and then come out where it's being evacuated by the Fan. That's why we have the circulatory fans within the canopy and it's why we lollipop to. To take those leaves out lower down to allow air to flow around so that we don't get dead spots from a moisture point of view, from a humidity point of view, which can cause rot and mold, but also so that we can get CO2 into the canopy and in and around the canopy in every place. It's interesting, actually. CO2 meters have become cheaper as well. So I. I bought my first CO2 meter about six or seven years ago and it was $450 and it was. It wasn't very good either. Whereas they now have these. They're basically environment sensors. You know, is your air good or bad air quality sensors? And they use a. It's a derivative sensor. It's not entirely accurate, but it's good enough for you and me. Me and for some people, particularly with large grow rooms, I'd suggest to you, buying one of these things, they're less than $100. You can you get wireless or, sorry, Bluetooth connection, all that stuff. But putting it, put it in different corners of your grow room and, and see what the level of CO2 is in there, and you'd be quite shocked. I think that the plant uses up CO2 relatively slowly, but the airflow in a lot of grow rooms is not, as I said, what would you call it, penetrating through the canopy? You know, it's not sort of washing out the. Or refreshing the CO2 in all parts of that canopy. So, yeah, it's not just. It's not supplementing with CO2 I think is a problem, but it's. It's controlling that environment as a whole. Having good thorough airflow going through it to all spots to. To make sure that the CO2 doesn't drop below, you know, atmospheric level or close to atmospheric level. But it's not necessary to have elevated CO2, you know, for running, say, par. Par at 1200, for example. You don't have to.

That's interesting. I. So living in the Pacific Northwest and growing, having a grow in my garage where I can't condition the air. I don't have a lung room. It's not in my house, which is already, you know, conditioned air that's at a good temperature. I can't just bring in fresh air consistently or my. It would typically be too hot or this time of year it might be too cold, but the air quality in terms of temperature would vary quite a bit. So.

So.

I went with, I went the route of, you know, quote unquote, sealing my room. That doesn't mean it's fully sealed. I still do have to do air evacuations, but I was monitoring CO2, and when I wasn't supplementing CO2, I found my CO2 levels would drop down quite low, 100, 200 on my meter at various stages of growth. And then at other times it was spike because of all the microbial life in the soil, as well as the plant itself will let off CO2 as well, especially during nighttime. So I would have. I would have to evacuate that for being too high. So I think CO2 management is important. And I definitely did see much better plant growth, especially during what we call that stretch period when the plant's really bulking and putting on in flowering, you know, let's say week two to four kind of range of flower where CO2 supplementation made a huge difference in plant growth. But to your point, I think for a lot of home growers that aren't in a, you know, garage space, you know, that maybe are in a tent, in a house, absolutely. It does not make Sense to supplement CO2. And, and I think you brought up a good point that these, you know, mushroom kits and those sorts of things are not really doing a lot.

Pointless. Totally pointless. Yeah, totally pointless.

I added under canopy airflow, some. Some docks, duck socks, essentially, with the use of, like, greenhouse convection tubing as a way of pushing CO2 up through the canopy more efficiently. And that worked really well for me. But, yeah, you brought up a good point. Air is not just homogenously moving through our room, and so we really have to think about that. And airflow is. Is a fascinating topic. I've had Dr. Nadia Saba on the podcast. You should. I'll have to introduce you to her if you don't know her, because she is really the best when it comes to airflow. And it is complicated to say the least, but it's absolutely something that you want to be thinking about as a grower in relation to all of this. But I, I didn't know that about. About light intensity without CO2. So that. That's something new to me and I appreciate you sharing that. I will have to do some more experiments with it.

Yeah, yeah. So it neatly brings us in. You're talking about, you know, how to ventilate the canopy and using these air socks, which I think are an excellent idea, that diffused air is. Is a really good idea. Like, it's, It's. I'm. I come from a background where I Worked in wastewater treatment many years ago and odor was a big problem. And we used to, you know, it was the other way around is trying to extract air seamlessly and treat it and get the odor out and scrub it and everything, but a little bit like, you know, the smell in the grow room. But I learned a lot then about the complexity of airflow and the difficulty in getting it to do what you want it to do, where you wanted to do it. Particularly when a room is congested, it's very hard for air to push through any sort of resistance, you know, so any sort of barrier. But when you're talking about those air socks, it reminded me of intra canopy. And we were speaking earlier about, you know, advancements and intracanopy is one of those. But it also weaves in nice and neatly with light intensity. And the reason it does is we spoke offline about fluence. I had Dr. David Hawley on from Fluence recently who've been innovating in the intracanopy space or under canopy space. And they have also been very generous with the data that they've built up from both on a meta front, you know, so working with lots of different companies and sort of collating lots of different grow results together, but also on specific controlled experiments. And what they found is, so say if we go back to our example of say 900 PPFD, so we're in, let's say we're in a 4x4 tent and we've got a 500 watt light above and it's delivering an average of 900 PPFD. What? And I want to get more out of that space. And I'm listening to this conversation, I'm thinking, right, I'm going to get a 750 watt light put in there. I'm a pro grower, I'm going to push that power intensity up really high. You can do that. Your light intensity on the, on the top of the canopy will be, you know, an average of 1300 more in, in some places lower than others. And you should get close to a 50% increase in yield. However, you are running that risk of, you know, you're into that zone where you could get some damage from, you know, light bleaching or whatever. Another way of tackling that problem is to keep my 500 watt LED light and add 50% again. So going up to 750 watts. But to putting the 250 watts underneath and shining it up. And what the studies of intra canopy setups like that versus top canopy setups is that the yield will be almost exactly the same. So it's not a magic sort of solution under canopy lighting where you get more than, you know, one unit of, of growth per, per watt used or whatever. It's, you get the same return putting a watt of top lighting as you do putting a watt of intra canopy lighting. They did notice some sort of side benefits or other benefits from it though, which were that the quality of the buds in the lower part of the plants improved. So from a commercial perspective, you know, they talk about grading grade A, grade B, grade C, grade A being your sort of, you know, your big nugs, quality nugs, the sort of, you know, for your bags and grade C being sort of probably going more towards concentrates and extracts and stuff like that. So they're of lower value. And what they showed is that they, they can improve the grading so they, they bump up a load of buds that would have been C grade into B and from B into A. But it doesn't affect yield overall as in, you know, whether you do it on the top or, or underneath, it makes no difference and it doesn't affect quality, but it has this, it helps growers push the intensity higher and manages the risk of that light bleaching and that plant stress from above. However, and the reason your socks came into the discussion was that you can end up with problems with heat then in the canopy because you've now put a lighting fixture down underneath your canopy which is going to be rising heat going to be rising from it up into your canopy and you need to be able to deal with that heat. So using, using those socks alongside intracanopy lighting means that you're providing airflow around the light but also through the canopy to dispel and get rid of some of that heat. It's not a massive amount of heat with the entra canopy, but it can be enough to cause people problems.

Is there a so, so two questions. Well, one clarification first. So you're saying that a 500 watt light plus 250 watts underneath is equal to, in terms of yield, a 750 watt light. So above. Oh, 750 watt light above. Good, good clarification. Okay. And our yields are not going to change, but the core quality of the buds may go up and there's less risk associated with light bleaching and some of these other impacts of too high of light from above. Okay, awesome. So my question is, is there a minimum amount of light in terms of wattage that we want in an under canopy light? Like would a 15 watt shop light do anything for me underneath or it'll.

Do, it'll do something, but it'll be proportional. So you, you know, if you have a 500 watt light above and you put a 15 watt light below, you're going to get 3% more yield. You know, is that worth doing? Congesting stuff, whatever. So it's proportional in terms of the ratios between top light and under canopy light. There's, it's a rule of thumb basis really, and I don't think it has been experimented on to the extremes, but the rule of thumb seems to be about 2/3, 1/3 or 3/4 to a quarter. That sort of ratio of top light to under canopy light. I think the heat is going to be an issue if you go much more on the under canopy and then obviously from a top light point of view, you're going to be going to end up getting into. If you're really, your people who are doing this are going to be pushing things as far as they can. That's, that's the reason they do it. So you, you, you want to alleviate the power intensity or the potential of stress and power intensity on the top. So it makes sense to put as much underneath as possible, but not so much that you get heat stress underneath.

That makes a lot of sense. Perfect. Sorry, I am. I have a couple questions here that are kind of maybe more rapid fire questions. I'm going through my list of things that we, I wanted to cover with you. I've heard changing topics a little bit. I've heard that with LEDs, sometimes you get certain cultivars use a lot more magnesium. And it seems like with certain growers, commercial growers we work with, they've supplemented magnesium and that seems to have fixed some of the issues. Is there any research to support this or have you seen this?

That LEDs, it's not my nutrition, nutrients now is not my area of expertise, but it's, that's sort of bugging me now because I saw something not so long ago, maybe a year ago that I think dispelled that myth. But I can't remember for sure. But like from a, from a science point of view, the plant, you know, from a nutrient uptake point of view, the plant is not going to perform very much differently if you have a HPS light above it or an LED light or fluorescent or whatever, the plant doesn't know where the photons are coming from. You know, it doesn't know that it's an led. LED photons are not any different from a Photon coming from hps, they're just in different proportions. I think there was some issue in early days. You know this Cal Mag thing where people say, oh yeah, you gotta add calmag and all that stuff. I saw that a lot. But there was also a lot of weirdness going on around the time around people allocating all sorts of problems to all sorts of solutions. That didn't seem to make sense to me at the time too. I haven't heard that calmag thing in about five years. Years.

The cow Mag thing would support this idea of higher magnesium because it is a higher ratio of magnesium but calcium.

But interestingly enough, as I said, it seemed like a misdiagnosis at the time. And to me, the fact that nobody is raising it now, sort of, that, that was a good few years ago. I would have heard that on a regular basis. Like there wasn't a week went by that I didn't hear something about somebody saying if you're using LEDs, you got to supplement Cal Mag and all that stuff. Yeah. But I, I haven't heard it in four or five years. So I'm, I'm, I, I, I can't say, to be honest, but I don't think it is the case.

Yeah, I haven't correlated it with, in terms of the commercial growers who have said this to me and I have seen some soil tests that seem to show more magnesium deficiencies. As a general rule though, for people who are growing and living soil. Soil I would say do not supplement magnesium without a obvious magnesium deficiency or a soil test. Because in general with living soils we tend to have sufficient to high magnesium relative to our other cations. So I just want to preface that as a fertility person, but I do have a couple commercial facilities that, and, and I'm not sure what brand lights they're using now that we're saying this, I might have to find, follow up with them on that. Maybe there's a spectral thing there that's going on.

I doubt it.

No, I doubt it. Okay.

I did it very much like, you know, from a physiological point of view, you know, the, the, the photosynthesis. You know, you can grow a plant, for example, just using one wavelength of light. You know, the photosynthesis will occur. The plant may look a bit strange in the end, but like if you, if you, if you look at the broadness, particularly under LEDs of the spectrum, that it's providing a little bit of everything in the spectrum. So there's no deficiency in the spectrum. We're not pushing a plants at any light intensity that they're not capable of elsewhere. So I suppose another way of me putting it was it would be, yeah, maybe there's deficiencies, but I'd highly doubt that they are specific to the light source. So I don't think if you change the light source, it's going to change that deficiency situation. Does that make sense?

Yeah, yeah. I mean I think we're making a big assumption that PAR levels and didn't change dramatically.

Yeah, yeah. Some other factor might have changed. Yeah, yeah, yeah, some of that.

You know, when people transitioned to LEDs originally. I will say that from, from I went to photo X a number of years back. It's an event that fluence would put on really phenomenal, cool event with some amazing speakers like Dr. Bugby was there in the past and I learned a ton about photobiology. One of the things, one of the experiments that Dr. Hawley did was who you mentioned was he grew basil out with all of these different spec spectrum. So same light intensity, same media, same nutrients. And you would see a dramatic difference in not just the color of the basil, the height and overall yield of the basil, but also the flavor of the basil because we got to taste them all. So we, we do know that spectrum has an impact on photobiology, on, on plant growth.

Yes. However.

Yeah, you go ahead. What's the caveat with that?

I. I would just say that, that it would be. Have been. So if you talk about the power spectrum. So again that that base, you know, it's like the, the meat in the pie or whatever, you know, provides most of what you need. That was probably stayed pretty consistent and it was probably varying other factors. So for example, with UV you can affect the coloring of plants, for example, or with spectrum you can bring out for example the purples, anthocyanin in plants. You can use UVB to increase oil production to basically make them, you know that with basil, you know that more aromatic and things like that. All I'm saying that is with cannabis specifically, similar experiments have been done and very little variance has been observed. And if you look at what their spectrum are now, they're just generic off the shelf spectrum. They basically have two spectrum and one of them's got really high red in it, you know that 660 nanometer and one doesn't. And that's pretty much it. That's from fluents themselves. That's not to say that they go into a particular grower with a particular strain that they have particular knowledge of and they're not able to Squeeze some, you know, get it to flower a little bit earlier, get it to stay a little bit shorter and more dense and whatever, you know, that they can, they can get marginal improvements with some strains within that power spectrum just by adjusting maybe the, you know, the color temperature, the quantity of the proportion of blue. But you know, I just interviewed Dr. Hawley there a couple of months ago and we, you know, he confirmed really that far red, for example, does very little, that you kind of want a lot of red for efficiency but not too much because it'll photo bleach. And that was pretty much it. You know, I could summarize our hour conversation with spending most of our time chasing down myths and you know, you know, disproving them. And you know, I think there is something in, in our brains that wants there to be something that we can do that sort of, it's not magical but you know, gives us a better return than just doing more better, you know, that there's something sort of.

Absolutely.

We can, we can get a little dial that we can turn here. And it's just going to, you know, our previously sort of unremarkable grow, it's suddenly going to be the highest quality thing that ever. But I'm sorry, there is zero evidence that it exists. And I think the HPS led, HPS is a classic form of this and it, it encompasses a couple of aspects that people will tailor their growing style to, to the equipment that they have. So in terms of their environmental controls, probably possibly their genetics, their medium, everything else. So for example, HPS growers developed methodologies of managing optimizing their grows with HPS power intensity, spectrum, heat output and everything. And then they switch to LED and go. And something goes wrong or it's not as effective. And they go, LEDs are terrible. And it's like, well, maybe you're terrible. You know, maybe you need to open your mind a little bit and go, well, I didn't just test change the light here. I changed the light intensity. I changed the amount of heat being put out into the room. I changed the amount of radiated heat that's radiated onto the top of my plant canopy and onto my buds. You know, there's a whole host of things that you need to alter in order to match your environment with your light source. But with the LED versus HPS stuff, I've been doing it for years and I brought it to a head the end of last year, or was it early this year anyway, recently, because there are studies out now that show that there's actually dis improvement with HPS is less good at growing quality weed than led. So there's evidence out there to show that. And there is zero evidence, nothing anywhere showing that HPS grows better than led. Nothing. And I have to say, if I was a HPS manufacturer somewhere over the last 10 years, I would have got my finger out my ass as my business was going down the toilet, and I would have, you know, got one of my many growers to prove that HPS is better than LED if it was the case. And I would have evidence and I'd be publishing it like crazy and I'd be selling HPS bulbs wherever I could guess what, there's nothing out there. Nothing.

So that was one of my questions, is there are growers that swear HPS weed is better. Now, if a photon is a photon, there can't be a lot to that claim with the exception of radiant temperature. You know, radiant, yes, on the leaf surface.

But you know what, there's lots of controlled experimentation has shown that higher bud temperature in the last few weeks of flowering results in lower quality harvest. And, you know, it's very intuitive to me. You're, you're going to be evaporating those compounds of the plant. If you can smell a plant, watch. You know, the goodness is about simply evaporating off that plant. So, and not just that, but the bud, because of the radiant heat, your bud quality, your bud temperature will be much higher than the room temperature. So say, you say I want to have, you know, 25 degrees centigrade, 80, 80 Fahrenheit, whatever it is, room temperature, and you're controlling it to that. Well, that's fine in the spot that you're measuring the air temperature, but the bud temperature with the radiant heat from HPS is going to be 4 or 5 degrees higher, particularly where it's a large bud and it soaks up that radiant energy and has a lot of difficulty in getting rid of the heat. So every bit of evidence that's out there objectively says that HPS is for, on a fundamental level is going to be less successful growing quality weed. And, you know, that is not to take away from people who say, I grow better H, I grow better H weed under hbs. That's a different statement. It's a reorder of things. And you, you know, I'm not saying that they're lying or they're not correct. I'm saying that it's a different argument we're having.

Yeah. That reminded me of another question I had. Just because I, I hear these Things and I, you know, I, I want to know what the actual research is around them. So I really, I really appreciate you diving into that a little more. So, so all that being said, LEDs really are sort of the future of, of growing technology. Pretty much in every way they're superior to HPS is essentially what I'm hearing you say.

That's what all the evidence says. Yeah.

What about then these, you know, plasma lights or, you know, ones that mimic the sun and some of those things that I hear about. Have you done any research on those or seen anything?

No. Well, I know, I know plasma lights. So. Plasma lights. So first of all, even people believed up to recently, I hope I've helped to dispel it, that say ceramic metal halide lights emit parts of the spectrum that LEDs can't or don't, and that's not true. So one of the big myths is that they emitted a lot of uvb. Well, they don't because glass blocks uvb. And so, you know, when you have a gas ignited in a glass tube, it can't escape that glass tube. However, there are tubes that are made specifically to allow the UVB to emit or to pass through and then, and then combined with certain gases in that, in that tube. So you can, you can generate a wider spectrum of light where you go down deeper into uvb. So you go, go down from blue down into uva, into uvb. You don't go to UVC because that kills things and we don't want it. And it goes further up more consistently into far red and then infrared, which is heat. But, you know, reference, the last hour of discussion is not going to make a huge amount of difference because it's not going to do anything. And yes, it's a, it's a nice broader spectrum. I remember switching from HPS to ceramic metal halide, God, 15 years ago now or whatever it was. And I loved it. And it was just the, the, if the light was so clean and so crisp and all of that. And I think I thought my plants were happier because I was happier with the light. I just thought it was a nicer light. So that's what convinced me. But no, there's again, there's no evidence. Zero. So, you know, if this was the case and people talk about checkerboarding, which is it?

I'm glad you brought that up.

Yeah, that kind of boggles my mind. I'm still struggling with that one. And it's people who are experienced, right? So they're doing it for a reason. Like they've, they've gone one way and it didn't work and they've gone back this way and it's working again for them, or it's a compromise they can accept or whatever the case is.

But, well, they're chasing a very specific plant expression that they got with HPS that they can't reach recreate with LEDs. That's the common thing I hear. It's like I'm losing this note on this bud that I got consistently with the hps. And what I'm hearing you say is from a science perspective, based on the research, there's no reason they should be losing that. And that's something related to some other environmental.

No, all I'm saying is there's, all I'm saying is there's no evidence to support it. That's all I'm saying. So, like, I'm not going to say anything absolutely. One way or the other, I hope. I haven't said anything. Absolutely. I'm just saying, to the best of my knowledge, with all the research that I've looked at, and I've been in the LED lighting game for over 10 years now, and my ear is pretty well to the ground and I do a lot of podcasts with the likes of yourself and lots of other people who are in the industry for longer and have, you know, our doctors and professors and all this stuff who I trust, and they have not found any evidence, therefore I can't say that there's any evidence that is the case. You know, again, if these guys are producing, I don't know what it is even that they're getting the benefit on. So whether it's, when you say expression, you know, is it certain terpenes or whatever, you know, I don't know what it even is that they're talking about. And if they are, they're probably going to keep it to themselves because that's, that's their knowledge and that's their value. But there is nothing published. And as I said, don't you think if I was a Gavita or whatever, and I still had, you know, I had a large market in the HPS game that, and, and there was evidence out there that I would have chased that down, I would have done what would have been, you know, relatively inexpensive studies to save my business, you know, to save my industry, which is making high pressure sodium bulbs and reflectors and all of that good stuff, that's my, you know, it's not my drop the mic moment, but it's my, you know, put that in your pipe and smoke it. You know, it's like, come back to me with that one encounter, that one. Because most of the. Most people who are like, oh, but it's, you know, it's sort of conspiratorial almost, you know, the sort of belief in it that it's like, yeah, but you don't have any evidence of the country. And it's like, well, you don't have any evidence the country. And, you know, there's a little industry that has died without having that evidence. And you would have thought, being experts in the industry and supporting that and using that technology, they would have somehow done an experiment along the way and maybe stuck it on the Internet for people. I think that as a base, probably would have been done. And yet, you know, I'm asking you, from what I gather from you, you haven't seen anything either. Nothing objective or controlled, which. Which proves this theory that, you know, you can get overall a better product with HPS than with other light sources.

I. I will say that the folks that have told me this are excellent growers.

Yeah.

I want to preface it with that.

Yeah, yeah, yeah, yeah.

They very much understand the expression that they're getting from their plant.

Yeah.

Are chasing something very specific, which makes me think maybe the angle here is to look at some sort of environment, environmental change caused by the switching of, you know, from HBS to led, as in, like we said, leaf, Leaf temperature, for example.

Absolutely.

Would probably be a big thing to look at. Probably the first thing I would look at. Or some other environmental change in the room. One other question I had around that, though, is this idea of light penetration. Is there any difference if a photon's a photon, Assuming it's the same spectrum, are we getting better penetration from what.

What do you mean by penetration further into the canopy?

Because here is a marketing term with a lot of different lights.

Okay, so I've got posts online on. On YouTube and on Instagram demonstrating this. I might need to refresh them and put them out again. But. Okay, so if I put a power sensor above a leaf, and it measured 900 micromoles. Okay. So that was our average power intensity. Getting it right up there. That's great. If I put it underneath the leaf, how many micromoles do you think I'd be measuring? One leaf.

None, if any, or very little.

Between about 5 and 10% of that. So it'll be down between, say, 50 and 90 micromoles. Okay, so now at 50 micromoles. Right. Nothing grows. So if you put a plant in 50 micromoles it'll do nothing. It'll die. You need to be up at about 150, 250 for the system to get going, for photosynthesis to activate and to be worthwhile doing so. Below one leaf of your canopy, nothing happens. So light I, I perceive what people mean by light penetration. I've kind of thought about it in a couple of. I think it, it, it means different things to different people. What it means to me is about multiple light sources. So if you have a canopy, as you say, it's all sort of uneven and there's buds popping up here and popping up here, and I'm talking about light coming at those buds and those leaves from lots of different angles. So with your typical LED bar light, you've got multiple light sources. Basically it's coming at you from all angles. With your old hps, particularly with a small reflector, you would have a very concentrated in the center radiating out so that the buds at the edge would have had a shadow. They would have been getting light on one side and not on the other. So for me, that's light penetration after that, you know, if I record. So when I do my PAR tests, for example, my system tests, I hang a light in a room over a test area and I've got reflective walls and I measure those. I measure the amount of light impacting that surface and I measure lots of different points. And I can get an average if I measure that at say, say I hang the light one foot above that test area, I will get say 900 micromoles if I double that height. So hang the light two foot high. Now I've got reflective walls, remember, So a lot of that light is going off the sidewalls and coming down onto the target area, still representing the plant canopy. But it'll drop by about 10%. Doubling the height will drop it about 10%. When you got reflective walls, and that's because of reflectance losses, more light is bouncing off those sidewalls before it reaches the plant canopy. It's actually heating the sidewalls instead of, you know, reflecting down and you get a reflectance loss. Now in terms of, of if you take those walls away, the light loss reduction will be a lot more. But some, sometimes I think people think that's penetration, you know, like how deep does the light go? How high can I lang it? Basically that it'll still be intense on the plant canopy. And that's a bit of a misnomer because you want your light as close as possible to the plant canopy, particularly with LEDs, they're not emitting radiant heat. You can bring them within 2 inches of a leaf and you won't get burn. You might get light bleaching over time, but you won't get radiated heat burn unless it's very, very close, like within a couple of inches. So you want to bring that light down as close to the plants as possible. Now, I think that some people, particularly coming from hps, thought that was like a sign of weakness, that if you, if you had to bring that light close to the plant canopy, it was because it wasn't a strong light source and because they. What they were used to is having basically a cone, which is their HPS reflector, which radiates heat down like this. And if they put it too close to the plant canopy, they would just get loads of heat in the center and very little at the edges. So they had to raise it quite high in order to. To get an even spread and so that the canopy wouldn't burn from the radiated heat. So I think there was a perception switching some for some people that LED lights don't penetrate as. As much, I. E. They don't. The light doesn't reach as far down in the tent.

Well, as the photon travels further from the source, it. We get less lower ppfd.

No.

Right.

No.

I mean.

Well, no. So wait, wait, I gotta argue two extreme. Two extreme examples. One is a bulb suspended in the midair. Light is radiate. Radiate out in all directions. Yeah. And in that case, if I hang it, if I have it one foot away and I double it to two foot away, the light intensity that I read from that bulb is going to be a quarter of. Of the intensity.

Okay, That's. That's what I was.

Yeah, but that's for. That's. But, but imagine a different scenario where I have a light source up here and it has lay. It has mirrors and lenses and it collimates the light. Okay. So the light coming out there, it's like a laser and it comes out in the same width all the way down. If I measure the light one foot away and two foot away, there might be very little, a small amount of difference, but it'll be very. The reduction will be very slight, be very small.

So saying the light, if I measure under a, an LED bar light, let's just say at a foot versus four feet, there's going to be a significant.

Yes. Yes.

Intensity.

Yeah, but we've got to think of the circumstances here. So if I hang a bar Light which is a flat plane, and it's shining light in one direction. Okay. So first of all, I'm not shining light in both directions or every direction. So the light loss is going to be less because it's collimated in a way. It's directed in a way. Okay. But if I put reflective walls along the side there, I, I'm now bouncing the light that's reflecting away back in. So light that would have been lost. So take your light bulb. If I put a reflector around that so that the light is reflected down, and then I use reflected walls away at the sides. Do you think the light. If I double the distance, it's going to be a quarter of the light?

Well, I would think the reflection is going to diminish that.

Correct, Correct. Or else we wouldn't do it. Right, or else we wouldn't do it. Why would you use reflective walls if they didn't work? So it helps to contain the light and redirect it back onto that target area, the plank canopy. Now, with LEDs, as I said, if you use an LED light in combination with reflective walls. I've done the experiments, the videos are up there. All that stuff going from 1 foot to 2 foot will reduce the light intensity about 10 to 15%. And that's just through reflectance losses. That's quite high, by the way. That's a lot of light now wasted that could have gone into production and yield. So that's why I suggest people, you know, drop your light as low as is recommended and keep it close to the canopy, because you have less waste, you have less light loss. Now you might want to reduce the light tensity, but use the dimmer. Don't raise the light to do that. Use the dimmer.

Use less electricity. So what I was referring to was the inverse square law. I had to look it up. Yeah, I couldn't remember the name of it.

Yeah. And the inverse square law, if you look at any of the diagrams, it's a sphere suspended in spherical face, and it's measuring the radiant energy coming out from it in all directions. And there's a reason we use reflectors, you know, in torches and in cars and lenses, is because that's very wasteful. You know, your, your, your, your. The light diminishes very quickly. So, you know, twice a distance, a quarter of the energy. That's, that's a terrible. You know, that's bad. So we use, we use reflectors and lenses and reflective walls and all those things to improve that. So it's better Than a quarter. Okay. So principally, I think we're agreed that it's better than a quarter because we're using those other devices to reduce those effects. And with LEDs, first of all, you're only going out one direction, right? So we've halved that reduction already. And then we're using reflective walls on the side. And between those two things, as I said, you can reduce those losses from 80% to 15%. 10 to 15%. So science works, physics works.

Yeah. So to give you a little more context, I had one of the largest larger lighting manufacturers in the cannabis space in the United States tell me that the inverse square law didn't apply to his lights because they were more like lasers.

Yeah, that's correct. That's, that's what I've been saying. Yeah, that, that's a, it's an extreme analogy, but it's the correct analogy because.

Of this reflective, the reflective properties of, say, the sides and other things that are happening now.

If, if you take away the sidewalls, right, so you don't have any reflective walls and you hang bar light in, in space and then take those measurements, the reduction is much more extreme. I can't remember, but it's probably 40%, 50% light loss going twice the distance. So those reflective walls are very, use them, they're very useful. If you're in a commercial environment, usually where you have, you have a table, you have a little aisle and then you have another table then. So the light, it's, it, you've got overlapping lights, so you're not, you're not spilling out onto the floor and it's being wasted. You're spilling it out maybe onto a white floor and it's bouncing back up because you've got, just got plants everywhere. So you, you, you're, you're either, you're, you're, you don't need those reflective walls around it to, to contain the light.

As much, but the light's not penetrating deeper into the canopy.

What do you mean by penetrating?

I mean more photons reaching further into the can.

How can they. Because only, only about 5% of them will pass a single leaf. If you stand above a plant canopy and look down and it's solid green, that's what the light is seeing. So it can't see around corners. It can sort of bend around leaves. So it, if it impacts any leaf, 95% of that light is absorbed, period.

I mean, that makes a lot of sense to me. I think their argument is that it, they get less light loss further down Assuming that light's not hitting a leaf or maybe those photons are bouncing, but.

It has to hit a leaf. That's why we have a complete canopy. And by the way, if we didn't like plants are, are again, if they've developed over time so that they will collect and absorb as much of that light as possible. So you know, they'll orientate themselves, they'll move their leaves, they'll produce leaves in spaces where there aren't leaves already. You know, they're going to fill that space. And it is, it is a complete and utter myth. Again, I've tried to dispel it. I've done experiments, I've shown people, practical experiments. I've done all this, you know, you put, you go next facility you go to bring a light meter with you or even use your phone on one of these meters and have a look at what the intensity is. One leaf under the canopy.

Oh, I do, I do.

It's nothing.

Yeah, there's nothing drop off is huge.

Yeah. And there's a, you know, plants, plants have developed to absorb light. They're very good at it. And you know, they're not giving it away to some plant underneath them. So they, they absorb it all and there's nothing left for anybody else. And the penetration, like I don't understand what people mean by it. Do they mean that the light goes through the leaf? Does it go around the leaf? Does it like bend around the leaf? I just don't understand what it means. It won't go past the first level of the canopy. It will not do it. There is no way for it to do it. Unless you get transparent leaves. By the way, it's a good thing. It's a good thing as well because it means we need less leaves to absorb, you know, maximum amount of light. Like we don't, you know, otherwise you'd have to have like four or five layers of leaves because light would be going through and through and through and through and you'd have an inefficient plant.

You know, the way I've thought of it is a little different. So let's say we have a leaf at one foot below the light and then we have another leaf that's two feet down that's not being blocked by other leaves. So. So light is penetrating down there.

Yeah.

The idea is that a certain lighting brand or manufacturer will somehow have higher light levels at that two foot leaf because their light has, there's less light lost.

Okay, I'm going to use a water analogy here. Okay. Because you'll trust, probably you'll have a better intuition for water and a better feel for it. But a photon of light is a particle, okay? It's no different than a drop of water. So if I was to say to you I wanted to water the do foliar spray, right? And I want to spray the leaves, but I only want to do the top surface. If I spray the top surface of the leaves. So using your analogy, there was one up here and there was another leaf here, okay. And that leaf was 75% shaded, okay? It's going to get a little bit of water here. It's going to get none here, okay? I did not, I did not foliar spray that leaf. I didn't do it because, because, no, no foliar spray reached it. So, you know, if I have another leaf down here, again, which is at a lower level, it's getting nothing. It's getting absolutely nothing.

I guess, I guess the. So the question is if I want to be more specific here and, and to be clear, I don't really believe this. I'm just trying to state, better state the argument that I hear. So let's say I have two leaves in a growth chamber. I'm not touching a plant even just by themselves in a growth chamber. One, one leaf at one foot, a different leaf at two feet. Would one lighting manufacturer, let's on the LED side be able to say that if it's getting a thousand ppfd at a foot, have higher levels at that 2 foot level? Let's say they're at 900 or they claimed it, there's less.

So the only, the only argument for that would be so if there was no reflective walls and they had, say for example, they had lenses on front of the LEDs, which are into a plus and minus situation. So lenses absorb a little bit of light and they direct it a little bit better. But in a, again, in a grow room with reflective walls or over spills of light, it doesn't really benefit that much. It's why you see very few LED fixtures with lenses on the front of them. Because you're giving and taking away with the technology. And also by the way, you're enclosing heat in with the LEDs. So the LEDs run at a higher temperature and it shortens their life. So you'd have to have a very good reason for doing it. Some people do it and again, in my view, it's a marketing exercise. They may talk about light penetration, but it, you know, it's a gimmick to me. And you know, if in your analogy where you have a leaf up here and you leaf down here, yes, that is sometimes the case within a canopy. But generally you're just going to hang that light right down, close to that upper leaf and the distance between that upper leaf and the lower leaf is not going to be that significant that it warrants compromising your light by putting lenses on it. As in extra cost, extra cost, reduced light efficiency and extra heat on your LEDs, reduced life span. So it just doesn't, it doesn't add up.

Now I think I want to have you back on to talk about what to look for in a grow light because I think that's a really complicated topic and we're kind of, we've already been talking for a long time. Before we go though, last question. I personally really like covering covered diodes. I like a light that has some sort of glass or polycarbonate to protect the diode. Not necessarily like, I realize we're losing some efficiency like you talked about, similar to a lens, but I think in the real world scenario of growing where there's dust and overspray and things like that, being able to clean the area of glass or call it, you know, polycarbonate and protect the diodes in a real world scenario, I think that leads to higher efficiency and better light output than uncovered diodes. But what are your thoughts on that topic?

So most grow lights, so including mine, have an acrylic spray over the LEDs, the LED board. So they are coated in a thin acrylic spray and that's formal coating. Just to understand that's. It can be called that. Yeah, yeah, yeah, yeah. So some people use silicon. It's a bit sticky. You can sort of feel a bit of resistance on it. Some people use acrylic. So it's very hard and shiny. And that is protection, significant protection in my book for the LEDs, the addition of polycarbonate or acrylic or whatever over them. So as I said, it's extra cost and it has to be cleaned itself. And by cleaning it generally you're probably going to reduce its opacity. So it's going to, or increase its opacity. So it's going to block more light and reduce your system efficiency over time. But the bigger issue for me is about entrapping heat within the, the fixture so the LEDs are running at a higher temperature. Having said that, in a commercial facility where, you know, if, for example, you want to be able to spray without moving lights out of the way, and you know, that sort of thing that makes total sense to me enough for a home grower. And as you say, it's a cost benefit thing. You know, my lights will last longer because of this activity I'm doing. I'm going to endanger them, you know, or put them at risk. Most home growers, if they are doing it, just pull your light up and out of the way if you're doing a fold or spray or whatever. Now you do get a buildup of sort of resin on surfaces in a grow room over a long period of time. I don't know if you've ever hung a plug board in your tent for a long period of time and you take, you know, a white one and you take the plug out that you've been using for a long time and you can see the sort of white, the lighter area where you took the plug away and the rest of the thing has got of gone a slightly brown color, sort of like that color, you know, where if you went into somebody's house who smoked a lot, you know, that you'd get that sort of resin coating on everything, that sort of light brown coating. So you do get that coating in the, in the grow room and even in a home grow or grow tent, you'll get that coating over years and years of usage. But you can clean the face of an LED bar light, for example, just with soapy water, just warm soapy water. And that will clean the LEDs without damaging them. And you know, but that only needs to be done every years. We're talking three, four years, you know.

Yeah. Most of the growers we work with on a commercial scale are fastidious about their cleaning, at least a lot of the better ones are. And that ability to be able to wipe a bar down, you know, that has glass or polycarbonate.

Oh yeah, yeah, absolutely. For operational reasons, completely understand it. And it, it, it, it's a stronger, much stronger argument in that case. I, I, I, I'd agree 100%. Yeah.

But I, I really enjoyed hearing your take on that and, and I think we covered a lot today. I really appreciate it. I would love to at some point really dive into what to look for in a grow light with you because I think that's a, another fascinating topic. But yeah, sure, yeah, maybe we can do a follow up here soon. And I, I thank you so much for your time today. You're a wealth of knowledge on lighting.

Well, I should be at this stage, in fairness.

All right, well, I'll let you enjoy. I know it's evening over there in Ireland and it's morning over here in the United States. So I wish you a good evening and talk to you soon.

And good morning too. Thank you very much.

That was Shane Torpy of Migro and you are listening to the Cannabis Cultivation and Science Podcast. Don't forget to check out the podcast page page at www.kisorganics.com. just click on the Learn tab then podcast. And just a friendly reminder that we have a Patreon channel with a free 7 day trial and tiers as low as $5 a month. We do book clubs, special cultivation tips and tricks, monthly video hangouts to connect and share your grow and even give out seed packs and other gifts at certain tier levels. Your support of Patreon or sourcing your products through Kiss Organics is what supports the podcast and I really appreciate it. We also have the upcoming Cannabis Cultivation and Science Conference in Bozeman this year in September. More information available about all these things on our website. Thanks for listening.