More THC testing – UVA vs UVB vs near-UV

Stephenj37826

Well-Known Member
I see all these light with each manufacturers making claims as to what the extra colours are supposed to do,. What I never see is side by side grows showing a difference. In my experience adding whatever amount you were going to spend in funky colours, in simple 3000K LEDs rather would yield more and cover more floor.
Photon count is still king. That being said UVA is pretty interesting indeed.

 

ttystikk

Well-Known Member
I see all these light with each manufacturers making claims as to what the extra colours are supposed to do,. What I never see is side by side grows showing a difference. In my experience adding whatever amount you were going to spend in funky colours, in simple 3000K LEDs rather would yield more and cover more floor.
There's some evidence to suggest that 2700K fill spectrum yields slightly more but that's as much as I've seen. I ran 3500K and didn't have any problems so it must not be significant.
 

Grow Lights Australia

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Rollitup Advertiser
Photon count is still king. That being said UVA is pretty interesting indeed.

In my opinion it is – up to a point – and then it isn't.

Photons = photsynthesis. But Spectrum = photomorphogenesis.

That means photosynthesis can be tuned via spectrum. Two good examples of this are the Emerson Effect – which can accelerate photosynthesis with the same number of photons simply by altering the red:far red ratio – and shade avoidance, which is also affected by red:far red. There are other examples.

We know plants can adapt and that the light antennae complexes of chloroplasts can evolve as the plant grows to use what light is available. But we also know there are limits to how much of each spectra the plant can use and how it will respond to different ratios of red to far red, red to blue, and far red to violet – not to mention ratios of red to green to blue.

There have been plenty of studies showing how different spectra can affect the growth of different types of plants, especially the red:far red ratios and red:blue. There's also evidence of how UV (A and B) and violet light can affect growth, terpene and cannabinoid production. I've posted up examples of studies throughout this thread, but there are many others out there for those willing to look.

We also know that photons can drive photosynthesis up to a point: after that point, when the chloroplasts are saturated, any excess light can cause heat build-up, with leaf temperature rises and eventual burning and bleaching.

So you need enough photons to maximise photosynthesis, but no more. And we can enhance photosynthsis – as well as alter photmorphogenisis (which can accelerate or retard different phases of growth) – by providing the correct ratios of certain types of light.

The question then becomes, what is the optimum amount and type of light for a particular plant at a particular phase of growth? You can throw all the photons you want at a plant, but if they are all green, the plant dies. And if they are all blue, then the plant is severely stunted. And if they are all red, then the plant will still not reach its full potential until a small amount of blue and green are added.

But I think we already know this.

Efficiency of a LED fixture is not hard to improve. But it is much harder to improve total LED fixture efficiency with a balanced spectrum.
 

Grow Lights Australia

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Rollitup Advertiser
Same number of photons, very different looking plants.


This is a good link, but it really only scratches the surface: https://www.valoya.com/ratios-in-the-light-spectrum-a-brief-overview/

I also note that Valoya is quoting the same study that we used to develop the first High Light with added near-UV (400-420nm) and elevated levels of far red: https://www.karger.com/Article/Fulltext/489030

EDIT: I've just realised it was one of their fixtures with the NS1 spectrum that was used in the study.



And here is another good article with real-world examples (above) of how spectra affects growth (photomorphogenesis): https://www.growertalks.com/Article/?articleid=24033

We've also done our own tests, but that is the subject of this thread and the one that came before it.
 
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Grow Lights Australia

Well-Known Member
Rollitup Advertiser
I see all these light with each manufacturers making claims as to what the extra colours are supposed to do,. What I never see is side by side grows showing a difference. In my experience adding whatever amount you were going to spend in funky colours, in simple 3000K LEDs rather would yield more and cover more floor.
Up to a point. But when you already have an even 1000 PPFD – or whatever target canopy intensity your strain responds best to – what do you do after that to improve yields and/or cannabinoid content?

Surely if you are an old-school grower you have seen the difference in yield and quality between a HPS, a MH and a CMH lamp? What could account for those differences if each lamp is emitting the same number of photons? Clearly it is spectrum. Isn't it?

We're not saying that numbers of photons don't make a difference. But we are saying that types of photons also make a difference. And we have done side-by-sides – that's what this thread is about.
 

Grow Lights Australia

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Rollitup Advertiser
Hey, Stephen, so nice to hear from you. I often wonder if just getting a reptile UV tube isn't enough... I know they are damn cheap these days.
If you're wondering, then perhaps refer to the first page of this thread if you haven't already. We're also doing another series of grows at the moment comparing the old High Red boards with 6% UVB Arcadia tubes vs the new High Light 420 board.

This is @Frank Cannon 's grow. Originally he was going to use a screen divider, but then he decided to simply separate each side with a couple of taller plants. So on the far left is Strain A + Strain B under High Red + UVB, and on the far right is Strain A + Strain B under straight High Light 420s. In the middle are two 50:50 sativas. While there will be some overlapping light in each corner, the majority of the light going to each plant in each corner will be from the source lighting which will at least provide a trend figure. There's also another test we conducted recently awaiting cannabinoid testing. I hope you can appreciatre it is not easy for us to do these tests under the current legal framework in Australia, but we are trying as best we can.

GrowOff.jpg
 

Grow Lights Australia

Well-Known Member
Rollitup Advertiser
There's some evidence to suggest that 2700K fill spectrum yields slightly more but that's as much as I've seen. I ran 3500K and didn't have any problems so it must not be significant.
There are many ways to skin a cat just as there are many ways to achieve 2700K. This is close to 2700K and CRI80 but is not like typical 2700K CRI80 LEDs on the market.

Screen Shot 2020-11-22 at 5.46.22 pm.png


Here's your typical Samsung LM301B 2700K CRI80 – hardly any far red, no UVA and no near-UV under 430nm either.
Screen Shot 2020-11-22 at 5.48.46 pm.png


I think I need to stop tubro-posting now.
 

Grow Lights Australia

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Rollitup Advertiser
is this on the market already? where can i get more infos?
That was a test spectrum. The final spectrum is the one below. We made the final decision based on the results we'd seen with the original High Light boards as well as the compromise between spectrum vs efficiency vs CRI.

The final High Light 420 board has a few percentage points more blue than the old UV boards, but significantly it has about 10 percentage points less green which was added to the red, far red and blue/violet/UV ranges. The resulting spectrum has twice as much far red and UVA/near-UV as the original boards.

The 405nm and 420nm peaks you see in the test spectrum were from the phosphor-coated blues we use, but they are very low in efficiency compared to the Nichia 5000K CRI70s we also use to boost the blue spectrum – 1.76 umol/j compared to 3.15 umol/j – so the decision was made to halve the number of PC Blues and increase the number 5000K Nichias.

We also wanted to increase the CRI to around 90, as we feel CRI is important for indoor gardeners so that they can pick up deficiencies and other problems early, instead of being masked by a low CRI. So all told it's a compromise spectrum that delivers excellent efficiency with "true" full PAR coverage and adequate amounts of far red and UV/violet to elicit growth and cannabinoid production. There is evidence to suggest blue light in conjunction with UV can increase cannabinoids.

Having said that, we can make the test spectrum any time we like. If there's demand.

Screen Shot 2020-11-10 at 11.03.42 pm.png
 
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Grow Lights Australia

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Rollitup Advertiser
damn, should look more often on your site. is there a thread for the new boards?
Not yet. I've posted up some spectral and efficiency readings and a few other bits of info, but we've been mad busy trying to get the new plug-and-play kits ready and I didn't want to start anything until we were able to deliver. We've done a lot of LED testing with LED Teknik over the past 12 months to see what the true efficiency of some of the LEDs were that we wanted to use, as well as conformal coating testing for waterproofing etc. It would have been very easy for us to make a 3+ umol/j board – maybe even close to 3.5 umol/j – but we also didnt want to compromise on offering a "true" full spectrum, as the results we've seen with the original High Light boards have been very good, both in terms of yield and cannabinoid content.

The new spectrum is really just an evolution of the old spectrum. We found a more efficient way to get the B/G/R ratios we wanted with twice as much far red and violet/UVA. In terms of energy, we think only a small amount of UV and near-UV is needed to stress the plant into producing more secondary metabolites, as it is quite strong. And because everything runs on one channel, it needs to run as long as the lights are on (12 hours etc), so there is a risk of damaging the plants with too much short-wavelength radiation exposure. We erred on what we thought was the safe side. But we're still playing around with other spectra so if we find something better we can incorporate it later.
 

dbz

Well-Known Member
Not yet. I've posted up some spectral and efficiency readings and a few other bits of info, but we've been mad busy trying to get the new plug-and-play kits ready and I didn't want to start anything until we were able to deliver. We've done a lot of LED testing with LED Teknik over the past 12 months to see what the true efficiency of some of the LEDs were that we wanted to use, as well as conformal coating testing for waterproofing etc. It would have been very easy for us to make a 3+ umol/j board – maybe even close to 3.5 umol/j – but we also didnt want to compromise on offering a "true" full spectrum, as the results we've seen with the original High Light boards have been very good, both in terms of yield and cannabinoid content.

The new spectrum is really just an evolution of the old spectrum. We found a more efficient way to get the B/G/R ratios we wanted with twice as much far red and violet/UVA. In terms of energy, we think only a small amount of UV and near-UV is needed to stress the plant into producing more secondary metabolites, as it is quite strong. And because everything runs on one channel, it needs to run as long as the lights are on (12 hours etc), so there is a risk of damaging the plants with too much short-wavelength radiation exposure. We erred on what we thought was the safe side. But we're still playing around with other spectra so if we find something better we can incorporate it later.
Will your new spectrum boards be available for purchase by the end of the year? I will be starting a new room in January and am interested in running them.
 

Grow Lights Australia

Well-Known Member
Rollitup Advertiser
how about some strips with the same spectrum? i can‘t really see me leaving that form factor, way better for even spread than any boards
I know there have been a few lively debates in these forums over strips vs boards, but all I'll say is it really comes down to how many boards you use. For example, have a look at Frank's grow a few posts up. He's got 8 panels in a 4.5' x 4.5' and has very even canopy lighting. You can do the same with strips if you're happy to wire them all up, but boards are a bit more convenient.

Unfortunately we don't have any High Light strips at this stage.
 
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