More THC testing – UVA vs UVB vs near-UV

Grow Lights Australia said:

OK, so can I ask why you would want us to put UVB LEDs on our boards? I'm just curious. We're always trying to learn what people want and the reasons for it. It's OK if it was just random question. We all ask those

Click to expand...

I don't like mixing components with vastly different ageing curves.
A chain is as strong as its weakest link.

I'm still not quite sure how much UV is required per square foot.. or maybe for a 4 or 5foot tent respectively,

ANC said:

I don't like mixing components with vastly different ageing curves.
A chain is as strong as its weakest link.

I'm still not quite sure how much UV is required per square foot.. or maybe for a 4 or 5foot tent respectively,

Click to expand...

According to cutter, read the very last portion at the bottom:

ANC said:

I don't like mixing components with vastly different ageing curves.
A chain is as strong as its weakest link.

I'm still not quite sure how much UV is required per square foot.. or maybe for a 4 or 5foot tent respectively,

Click to expand...

Randomblames posts in the UV thread and maybe also the Far Red thread touch on quantity, if you interested in going down the rabbithole.

ANC said:

I don't like mixing components with vastly different ageing curves.
A chain is as strong as its weakest link.

I'm still not quite sure how much UV is required per square foot.. or maybe for a 4 or 5foot tent respectively,

Click to expand...

I think nachooo was using 4 leds w total 60mW output for about 3hours per day together with uva
Edit: for 1m2

there is this guy from MIGRO company which produces lights, that has YT channel testing grow lights, and he has a good video on UV which i trust but havent tried out for myself, and it confirmes what @Morbid Angel said, and in other videos he recommended reptilian UV bulbs... link to video: there are other 2, should be in recommendations after this one... hope it helps!

Not sure, but I figured this test was done from clones and not seed? (for consistency)
Not knowing the intricacies of this test (or the plant itself), I would have thought this would be a reasonable base line:

Grow out one clone (from a known mother) without all the lights your testing (far reds, UV). Test that clone at a fixed harvest point (so all later tests can be harvested at the same point).

Then, using a number of other clones from the same mother (or, perhaps even from the first clone itself), run the original test with all the extra 'test' lights. Finally, compare the results.

What I would personally like is a
phosphor conversion UV LED.
Consisting of a 285 nm excitation source and a phosphor peaking at 385 nm .With a SPD curve resembling the shape of the one of 3000K 80Ra a pc white LED has.
So,in a single LED device both the UVB & UVA response triggering peaks will be included ,at a nice ratio between them .
That’s what I would like to use ...

SDS_GR said:

Frontiers | An Update on Plant Photobiology and Implications for Cannabis Production

This review presents recent developments in plant photobiology and lighting systems for horticultural crops, as well as potential applications for cannabis (...

www.frontiersin.org

What I would personally like is a
phosphor conversion UV LED.
Consisting of a 285 nm excitation source and a phosphor peaking at 385 nm .With a SPD curve resembling the shape of the one of 3000K 80Ra a pc white LED has.
So,in a single LED device both the UVB & UVA response triggering peaks will be included ,at a nice ratio between them .
That’s what I would like to use ...

Click to expand...

I know of work being done on phosphored leds but around 400nm

Puff_Dragon said:

Not sure, but I figured this test was done from clones and not seed? (for consistency)
Not knowing the intricacies of this test (or the plant itself), I would have thought this would be a reasonable base line:

Grow out one clone (from a known mother) without all the lights your testing (far reds, UV). Test that clone at a fixed harvest point (so all later tests can be harvested at the same point).

Then, using a number of other clones from the same mother (or, perhaps even from the first clone itself), run the original test with all the extra 'test' lights. Finally, compare the results.

Click to expand...

Yes, if you read the first few posts you'll see that the tests were done on the same clones, in the same media, using the same nutrient in the same area, but by different growers. The growers were all pretty experienced so there were no issues with any of the samples and they all looked similar.

There were no Far Reds tested. Have a read through the first few posts and you will see how the test was conducted. One test used straight High Light boards, another used High Red Boards with CMH and another used High Red Boards with UVB reptile bulbs. The aim of the test was to compare the same spectrum with the addition of near-UV (High Light boards), UVA (High Red +CMH), and UVB + UVA (High Red + reptile bulbs). So in fact, the test was conducted similar to the manner you described.

pahval said:

there is this guy from MIGRO company which produces lights, that has YT channel testing grow lights, and he has a good video on UV which i trust but havent tried out for myself, and it confirmes what @Morbid Angel said, and in other videos he recommended reptilian UV bulbs... link to video:

there are other 2, should be in recommendations after this one... hope it helps!

Click to expand...

That is quite an old experiment now (1987) and there are not a lot of other tests out there comparing different forms of UV but we do know that in our dealings with industrial hemp farmers one of the earlier issues they had was when they imported seed stock from China that was tested at <0.3% THC – which was under the limit for industrial hemp at the time – but when they grew the same seeds out under the Australian sun which has a higher UV Index it increased THC levels to >0.5-1%. This meant their industrial hemp was suddenly classified as a prohibited drug. The hemp farmers had to explain to the Agriculture Department here that higher UV increased THC and that UV levels were not only seasonal, but regional. The legislation had to be re-written to accomodate this phenomenon which is well documented amongst Australian hemp farmers. We used some of that research when developing the High Light board. Other research pointed to similar results being achieved with near-UV, which we have tried to prove in our own testing.

Grow Lights Australia said:

That is quite an old experiment now (1987) and there are not a lot of other tests out there comparing different forms of UV but we do know that in our dealings with industrial hemp farmers one of the earlier issues they had was when they imported seed stock from China that was tested at <0.3% THC – which was under the limit for industrial hemp at the time – but when they grew the same seeds out under the Australian sun which has a higher UV Index it increased THC levels to >0.5-1%. This meant their industrial hemp was suddenly classified as a prohibited drug. The hemp farmers had to explain to the Agriculture Department here that higher UV increased THC and that UV levels were not only seasonal, but regional. The legislation had to be re-written to accomodate this phenomenon which is well documented amongst Australian hemp farmers. We used some of that research when developing the High Light board. Other research pointed to similar results being achieved with near-UV, which we have tried to prove in our own testing.

Click to expand...

if only the austr. farmers would have used a drug-type form of Cannabis instead... and then claimed an enormous THC increase - due to the savagely raging austr. sun, of corpse

Kassiopeija said:

if only the austr. farmers would have used a drug-type form of Cannabis instead... and then claimed an enormous THC increase - due to the savagely raging austr. sun, of corpse

Click to expand...

Ah yes. I know that @Prawn Connery had been following hemp farmers for many years as it was the only form of legal cannabis allowed to grow in Australia and that he based his early design on the information they had shared. The only problem with the information is that the farmers did not know which part of the UV spectrum was mostly responsible for the increase, only that it was a problem for them if their THC levels got too high. This is a known issue with hemp production around the world.

Grow Lights Australia said:

Yes, if you read the first few posts you'll see that the tests were done on the same clones, in the same media, using the same nutrient in the same area, but by different growers. The growers were all pretty experienced so there were no issues with any of the samples and they all looked similar.

There were no Far Reds tested. Have a read through the first few posts and you will see how the test was conducted. One test used straight High Light boards, another used High Red Boards with CMH and another used High Red Boards with UVB reptile bulbs. The aim of the test was to compare the same spectrum with the addition of near-UV (High Light boards), UVA (High Red +CMH), and UVB + UVA (High Red + reptile bulbs). So in fact, the test was conducted similar to the manner you described.

Click to expand...

Ahha. Thanks for the info

nDanger said:

I've been following your work with great interest and commend you on all your efforts. I have my main lighting set up satisfactorily, but wondered if you have considered producing a UV only lamp (like HLG's offering). I have 100 sq ft of canopy so theirs is a bit pricey! I have an unopened box of 8 Solacures I'll install in a few weeks (in the middle of harvest now) so I'll see what they do.
Here's an interesting read from a lighting company I hadn't heard of, discussing the uvr8 pathway and the synergy of uva and uvb.

The MetaRail™ UVB+A Lighting Instrument — AgricUltra™ Advancements

The MetaRail is designed to deliver the industry’s most advanced UV spectrum and power density in the optimal ratio of UVA:UVB wavelengths to optimize plant attributes—such as improving flavour in strawberries and increasing THC levels in Cannabis plants.

www.agricultra.com

Click to expand...

Very interesting, but can't find them for sale anywhere.
Sent them an e-mail requesting release date.

Sorry to derail the thread a bit with my questions @Grow Lights Australia

I hope it's okay to ask about stuff not entirely related to your products. I can't help myself. You guys really know your stuff!

I read with interest regarding the effects of near UV (400-430nm) on potency. I am currently using 3000k and 4000K QBs supplemented with 660nm and 730nm strip. I am adding a 390-410nm UVA Strip to it.

Would you suggest using this UVA strip for full light cycle, like in your tests? Or will it be too much? How long would you have it on? It shares a little of the near UV spectrum so I thought who better to ask than you guys?

nDanger said:

I've been following your work with great interest and commend you on all your efforts. I have my main lighting set up satisfactorily, but wondered if you have considered producing a UV only lamp (like HLG's offering). I have 100 sq ft of canopy so theirs is a bit pricey! I have an unopened box of 8 Solacures I'll install in a few weeks (in the middle of harvest now) so I'll see what they do.
Here's an interesting read from a lighting company I hadn't heard of, discussing the uvr8 pathway and the synergy of uva and uvb.

The MetaRail™ UVB+A Lighting Instrument — AgricUltra™ Advancements

The MetaRail is designed to deliver the industry’s most advanced UV spectrum and power density in the optimal ratio of UVA:UVB wavelengths to optimize plant attributes—such as improving flavour in strawberries and increasing THC levels in Cannabis plants.

www.agricultra.com

Click to expand...

strange what they write there:
"the UV effect can be had for up to 20 hours crossing the visible cycle and night cycles."

does this imply to leave UV on for the lights-out? I would think the UVA would interrupt it or prevent the plant from "sleep"...

Kassiopeija said:

strange what they write there:
"the UV effect can be had for up to 20 hours crossing the visible cycle and night cycles."

does this imply to leave UV on for the lights-out? I would think the UVA would interrupt it or prevent the plant from "sleep"...

Click to expand...

Interesting.
Seems like the quote comes from their pest control page. A possibility is that 295 might not reverse flowering? As you read on, they give references to literature. But near end of page mention that experimentation on effects on various types of insects. Leaves a lot open for interpretation, and suggests it is a speculative comment based off of research from others work.

end_of_the_tunnel said:

A possibility is that 295 might not reverse flowering?

Click to expand...

but it's activating plant receptors which also get excited by conventional blue light... not saying that's all there is to it.... I'm just not aware of any study which did do this (using UV light during the night phase)... but I could already see why it wouldn't work... as the CONSTANS gene (the photoperiodic flower inductor gene) gets activated by UV, too (though I guess UVA...)

What is interesting is impact on terpene profiles alongside changes in thc. Seems there can be losses as well as gains. Wonder what the levels or ratios of UV and/or other light in the mentioned recipes were? Both an A and a B recipe, and two cultivars. Scroll down page.


Think the example above highlights that we are flying in the dark when we try to fit possible outcomes of UV supplimentation in a box. Still a long way for us personal growers to go before we are able to tap in, analyse and adjust lighting. But the possibilities are there. Very fascinating.

Important to remember high cannabinoid test report results do not equate to good weed. They fit into a narrative that suits bulk processors, and others trying to sell something and recieve money. Sadly social media followers blindly buy into and perpetuate this cycle. You could argue its almost a form of pyramid franchise scheme. But hey, you do get hardware and some knowledge from the deal.

GrowGlowmj said:

Sorry to derail the thread a bit with my questions @Grow Lights Australia

I hope it's okay to ask about stuff not entirely related to your products. I can't help myself. You guys really know your stuff!

I read with interest regarding the effects of near UV (400-430nm) on potency. I am currently using 3000k and 4000K QBs supplemented with 660nm and 730nm strip. I am adding a 390-410nm UVA Strip to it.

Would you suggest using this UVA strip for full light cycle, like in your tests? Or will it be too much? How long would you have it on? It shares a little of the near UV spectrum so I thought who better to ask than you guys?

Click to expand...

Hi, sorry for not replying to you earlier but we've had a busy couple of weeks and I haven't been posting much lately.

We would recommend using it full cycle. 390-410nm is pretty much in the visible spectrum and does not carry as much energy as deep UVA or UVB, so we'd expect it to have similar results to the small amount of 400-430nm we have in our High Light boards. In fact, we're trialling some new LEDs at the moment and in one of the trials we've added about double the dose of 400-430nm compared to the current High Lights to see how it impacts cannabinoid yields. The trial is being conducted using the same strain and under the same conditions as those used at the start of this thread.

So far there does not appear to be any damage to the plants or any real down side. The same boards were used to veg the plants prior to flower, and the grower said they were the healthiest he had ever grown under LED. We suspected the vegging plants could take a good amout of UV, as there is more UV present in sunlight during the summer months when cannabis grows outside prior to flowering. We note some growers follow nature in adding UV to their vegging plants also.

As soon as we get the test results we'll let you know.