Latest UVA vs UVB cannabinoid test results

Kassiopeija

Kassiopeija

Well-Known Member
yeah after so many studies on that it gets obvious that the cited - and misunderstood - decreases in terps/cannabinoids are a direct result of increased dry harvest weight (= more light, more photosynthesis... even though UV-A, and esp. UV-B, can cause photoinhibition - but if overall ppfd is too low any additional light(color) will still help.
Tbh the scientists should do a review/meta-analysis on this topic and draw a ratio of weight:"active ingredients" to further clarify the subject at hand!
 
Speedtriplebbc

Speedtriplebbc

Well-Known Member
Any idea on a point of diminishing returns? It seems that around 3-4% uva are producing positive results in overall quality and allows more far red that can reduce the overall time and quality. So what if we aimed for 5-6% full cycle or even 10% uva? Then I’m thinking if you could add more uva then would that allow more far red and would there still be a benefit? I’m also curious about adding infrared but I think that’s another topic and definitely a separate channel.
 
Grow Lights Australia

Grow Lights Australia

Well-Known Member
Speedtriplebbc said:
Any idea on a point of diminishing returns? It seems that around 3-4% uva are producing positive results in overall quality and allows more far red that can reduce the overall time and quality. So what if we aimed for 5-6% full cycle or even 10% uva? Then I’m thinking if you could add more uva then would that allow more far red and would there still be a benefit? I’m also curious about adding infrared but I think that’s another topic and definitely a separate channel.
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Our original High Light 420 boards had only 0.5% UVA and and produced up to 25% more D9THC than generic 3000K CRI80 LEDs (Samsung QB288s). The Gen2 boards now have 1% UVA and we have already documented a 15% increase in D9THC over the original High Lights so I'm guessing that for a full-cycle light (12/12) we are pretty close to optimal. 3-4% seems like a lot to me though it would depend on the UVA wavelength. Our UVA is right around 400nm so 3-4% UVA <365nm would be pretty strong. 10% would probably kill your plants.
 
Kassiopeija

Kassiopeija

Well-Known Member
Yes, if you go overboard with UV the plants will just react to use specific sunscreen pigments to filter & block these potentially harmful lightwaves out.

Interestingly, plants have many different compounds for that at their disposal, that have varying absorption-max in order to tailor-suit the protection vs the incoming harmful rays. But it's not a bad thing per se, many of these substances promote good taste & have a high anti-oxidante potential - very healthy (e.g. for green leafy vegetables)

Also, UVA has a much better leaf-transmission than blue, and can help with photosynthesis in the shaded intra-canopy, and also reduce stretch there. Studies on the green-farred enriched shadelight have reveiled that a tiny amount of blue - 1umol - is already enough to counter the Shade-Avoid-Syndrome in sunplants, as the Phototropins are ultra-sensitive to blue.

Additionally UVA can cause a violet, blue & bluegreen leaf fluorescence, both adaxial & abaxial. Studies are very promising on that subject generally but also show individual reactions between species.

So it stands to reason to enlarge or enrich the typical white-light-only spec by a broad but low-fluence UVA spec.
 
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M

manbird

Member
Hi @Grow Lights Australia.
I am following your research/results/experiments with far red and UV-A for quite some time now.
I have a general question about the use of UV and hope you can help me out with your experience in this topic.

I have a pretty small space (0.6x1.6ft and a height of 1,9ft) and want to use UV-A and far red.
With only about 5 inches between the lights and plants I am concerned using UV-A could do more harm than it would actually help.
What is your recommended minimal distance between your panels and the plants in regard of UV burn?
Would you say 1-2 leds with 370mW of 400nm UV is too much at a distance of 5inches?

I hope I am not asking off-topic stuff here, and can remove this post if requested.
 
L

loco41

Well-Known Member
Kassiopeija said:
Yes, if you go overboard with UV the plants will just react to use specific sunscreen pigments to filter & block these potentially harmful lightwaves out.

Interestingly, plants have many different compounds for that at their disposal, that have varying absorption-max in order to tailor-suit the protection vs the incoming harmful rays. But it's not a bad thing per se, many of these substances promote good taste & have a high anti-oxidante potential - very healthy (e.g. for green leafy vegetables)

Also, UVA has a much better leaf-transmission than blue, and can help with photosynthesis in the shaded intra-canopy, and also reduce stretch there. Studies on the green-farred enriched shadelight have reveiled that a tiny amount of blue - 1umol - is already enough to counter the Shade-Avoid-Syndrome in sunplants, as the Phototropins are ultra-sensitive to blue.

Additionally UVA can cause a violet, blue & bluegreen leaf fluorescence, both adaxial & abaxial. Studies are very promising on that subject generally but also show individual reactions between species.

So it stands to reason to enlarge or enrich the typical white-light-only spec by a broad but low-fluence UVA spec.
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Really nice post. Always enjoying reading your input on these things. Threads like this and your posts make me realize how little I actually understand all this stuff.

I am no great grower by any means but I noticed my leaf colors having more of a blueish tint to them when I started using my original highlights compared to previous grows with 80cri cobs. Granted the strains were different and from seeds, so take all this as purely observational, but the several runs all carried that similar blue look on the leaves between a couple of different strains.

On my last run I used a 6%uvb bulb in between the highlights full cycle, even in veg. Again too many different variables to really even begin to say the added uv was the cause but I noticed the same blue tinted leaves along with a bit more purpling on the underside of a lot of buds.

Sorry I didn't really add anything to furthering the discussion, your post just reminded me of my first grow with the boards.
 
Grow Lights Australia

Grow Lights Australia

Well-Known Member
manbird said:
Hi @Grow Lights Australia.
I am following your research/results/experiments with far red and UV-A for quite some time now.
I have a general question about the use of UV and hope you can help me out with your experience in this topic.

I have a pretty small space (0.6x1.6ft and a height of 1,9ft) and want to use UV-A and far red.
With only about 5 inches between the lights and plants I am concerned using UV-A could do more harm than it would actually help.
What is your recommended minimal distance between your panels and the plants in regard of UV burn?
Would you say 1-2 leds with 370mW of 400nm UV is too much at a distance of 5inches?

I hope I am not asking off-topic stuff here, and can remove this post if requested.
Click to expand...
Hi mate, 5 inches is not a lot of head room. It's about 12-13cm. UVA wouldn't be an issue, but you would need to have the LEDs turned right down. I wouldn't be concerned about 0.5-1% UVA as much as I'd be concerned about overall light bleaching at that distance. But it all depends what LEDs you run and how hard you run them.
 
Rocket Soul

Rocket Soul

Well-Known Member
manbird said:
Hi @Grow Lights Australia.
I am following your research/results/experiments with far red and UV-A for quite some time now.
I have a general question about the use of UV and hope you can help me out with your experience in this topic.

I have a pretty small space (0.6x1.6ft and a height of 1,9ft) and want to use UV-A and far red.
With only about 5 inches between the lights and plants I am concerned using UV-A could do more harm than it would actually help.
What is your recommended minimal distance between your panels and the plants in regard of UV burn?
Would you say 1-2 leds with 370mW of 400nm UV is too much at a distance of 5inches?

I hope I am not asking off-topic stuff here, and can remove this post if requested.
Click to expand...
I think this is doable but you should make sure you have full control of dimming and timing. I think most of the time when people fuck up uv is by introducing too much at the same time. If you want to use uv in flower you should probably also have some in veg.
Start by pulsing it in for less than an hour in veg, low intensity and work up.
It also helps having one of those Volts/amp meters on your uv circuit so you can see exactly how hard your driving them.

370mW of 400nm is not a lot of output really. If this is your output on 350mA /nominal current then you should consider other diodes as these are likely older diodes, which will have shorter life and run hotter than youd like.
 
M

manbird

Member
Grow Lights Australia said:
Hi mate, 5 inches is not a lot of head room. It's about 12-13cm. UVA wouldn't be an issue, but you would need to have the LEDs turned right down. I wouldn't be concerned about 0.5-1% UVA as much as I'd be concerned about overall light bleaching at that distance. But it all depends what LEDs you run and how hard you run them.
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Thank you for your fast response.
Currently I am using a total of 110w of which half is 3500k Cobs. The other half consists of blue+red osram golden dragon.
Both these Led types are not the most efficient, therefore I never had a problem with bleaching.
Regarding your advice of about 1% UV I will aim for max. 1W of 405nm UV.


Rocket Soul said:
I think this is doable but you should make sure you have full control of dimming and timing. I think most of the time when people fuck up uv is by introducing too much at the same time. If you want to use uv in flower you should probably also have some in veg.
Start by pulsing it in for less than an hour in veg, low intensity and work up.
It also helps having one of those Volts/amp meters on your uv circuit so you can see exactly how hard your driving them.

370mW of 400nm is not a lot of output really. If this is your output on 350mA /nominal current then you should consider other diodes as these are likely older diodes, which will have shorter life and run hotter than youd like.
Click to expand...
After reading through this and some other threads I am aware that too much UV can be a big problem.
Therefore I am not sure what UV leds I should use.
I cannot use UV during veg because I am buying clones and putting them into flower after 1-2days.
Because I am using an arduino and relais I have full control over timing.
I need to do some research how I can dim the UV chips with the arduino.

My approach would have been to use UV during the last 4 weeks of flowering for about 4h max.

I did a mistake in my previous post. The UV-A chips I am considering to buy are Nichia NCSU275 with 385nm.
At 500mA they consume a total of 1,8W and emit about 350mw of UV light.
Using two of those chips would bring me to 0,7W of UV which would be right between the 0,5-1% of UV.
 
Rocket Soul

Rocket Soul

Well-Known Member
manbird said:
Thank you for your fast response.
Currently I am using a total of 110w of which half is 3500k Cobs. The other half consists of blue+red osram golden dragon.
Both these Led types are not the most efficient, therefore I never had a problem with bleaching.
Regarding your advice of about 1% UV I will aim for max. 1W of 405nm UV.




After reading through this and some other threads I am aware that too much UV can be a big problem.
Therefore I am not sure what UV leds I should use.
I cannot use UV during veg because I am buying clones and putting them into flower after 1-2days.
Because I am using an arduino and relais I have full control over timing.
I need to do some research how I can dim the UV chips with the arduino.

My approach would have been to use UV during the last 4 weeks of flowering for about 4h max.

I did a mistake in my previous post. The UV-A chips I am considering to buy are Nichia NCSU275 with 385nm.
At 500mA they consume a total of 1,8W and emit about 350mw of UV light.
Using two of those chips would bring me to 0,7W of UV which would be right between the 0,5-1% of UV.
Click to expand...
Just because you hit the total wattage level doesnt mean you have that properly spread: if your space is 6' wide (from what i understood) youd need a few more points of light to be able to spread that light out over the cannopy.

Nichia is a good brand but the efficiency on those diodes are real crappy. There are plenty of good diodes out there for cheap. Where are you buying from? Maybe this is all better for your own thread though as this is more of a specific issue rather than the general uv indo of this thread.
 
Grow Lights Australia

Grow Lights Australia

Well-Known Member
Rocket Soul said:
Just because you hit the total wattage level doesnt mean you have that properly spread: if your space is 6' wide (from what i understood) youd need a few more points of light to be able to spread that light out over the cannopy.

Nichia is a good brand but the efficiency on those diodes are real crappy. There are plenty of good diodes out there for cheap. Where are you buying from? Maybe this is all better for your own thread though as this is more of a specific issue rather than the general uv indo of this thread.
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The Nichia 405nm UVA diodes we use have been tested at around 72% efficient. But you are right about the spread so it might even be worthwhile buying more UVA diodes that are cheaper and less efficient so that you can spread them over the grow more easily. Or else maybe just buy a plain fluorescent tube as they all have a bit of UVA in them. The cooler the colour temperature, the more UVA the bulb should have.
 
Grow Lights Australia

Grow Lights Australia

Well-Known Member
manbird said:
My approach would have been to use UV during the last 4 weeks of flowering for about 4h max.
Click to expand...
Little know fact. THC levels normally peak two weeks prior to traditional harvest. However that's also the time the plant really bulks up. What that means is you are better off running UVA at least all the way through flower if not for most of the grow.
 
Rocket Soul

Rocket Soul

Well-Known Member
Grow Lights Australia said:
The Nichia 405nm UVA diodes we use have been tested at around 72% efficient. But you are right about the spread so it might even be worthwhile buying more UVA diodes that are cheaper and less efficient so that you can spread them over the grow more easily. Or else maybe just buy a plain fluorescent tube as they all have a bit of UVA in them. The cooler the colour temperature, the more UVA the bulb should have.
Click to expand...
Id agree. But since covid increased thw demand of uv led it seems like you can get decent uv led from many brands at decent price. 350/1800 isnt even 25% efficient. All in saying is if you buy those diodes just for the nichia brand youre probably missing out.
 
Grow Lights Australia

Grow Lights Australia

Well-Known Member
welight said:
I would be interested to know which 405nm leds are more efficient than the Nichia, not disagreeing but a little specific information than general statements Im sure would be useful to forum
Cheers
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Not sure I understand the question. Is someone claiming they know of more efficient UV diodes than the NVSU219CT? Because we haven't found any. That's why we use them.
 
Rocket Soul

Rocket Soul

Well-Known Member
welight said:
I would be interested to know which 405nm leds are more efficient than the Nichia, not disagreeing but a little specific information than general statements Im sure would be useful to forum
Cheers
Click to expand...
All im saying is that if ops prefered uv diode, nichia or other, has 350mW output at nominal 1.8w operation then thats poor performance for a 385nm diode.
 
M

manbird

Member
Rocket Soul said:
Just because you hit the total wattage level doesnt mean you have that properly spread: if your space is 6' wide (from what i understood) youd need a few more points of light to be able to spread that light out over the cannopy.

Nichia is a good brand but the efficiency on those diodes are real crappy. There are plenty of good diodes out there for cheap. Where are you buying from? Maybe this is all better for your own thread though as this is more of a specific issue rather than the general uv indo of this thread.
Click to expand...
I think you misunderstood the space I have available. I got 20cm x 50cm (7,8inches x 20inches) of space.
I appreciate the fact you are mentioning the poor efficiency of these chips.
After searching for another one, I found the NVSU119CT with 405nm which outputs 1,4w of UV at 2,2w.
Looking at the beam angle of this chip, it would cover my space pretty nice.
Considering my small space I think one of these at 700mA or less would be sufficient and has a way better efficiency than the first chips I considered.


Grow Lights Australia said:
Little know fact. THC levels normally peak two weeks prior to traditional harvest. However that's also the time the plant really bulks up. What that means is you are better off running UVA at least all the way through flower if not for most of the grow.
Click to expand...
So if I buy clones and put them into flower straight away, you suggest to use the UV from day 1 to finish?
With UV lights on everyday I would just experiment with the amount of time the plants are exposed to UV.
Maybe gradually increase the time from a few minutes to several hours every day during flowering.

Thank you all for your advice!
I am sorry for starting an off-topic discussion in this thread.
If I can find a laboratory in my area to test my results with and without using UV, I maybe can contribute to the original topic of this thread.
 
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