THC, CBD, Terpene test results – UVA vs UVB vs none

[nunyabidness420]

LED tech has one 280nm translating 80mA - is that much?

The most efficient 280nm LED to date does about 8~10% efficiency, this LED was announced late April of this year.
Assuming they're using that, it's putting out 8mW of UV light.
I'm running about 20mW for a 2x2.
Agricultra is running 350mW per meter squared.

 

[Kassiopeija]

The most efficient 280nm LED to date does about 8~10% efficiency, this LED was announced late April of this year.
Assuming they're using that, it's putting out 8mW of UV light.
I'm running about 20mW for a 2x2.
Agricultra is running 350mW per meter squared.

so is this sheet in error?

Luminus XBT UV 275nm-285nm auf 20mm Star - XBT-3535-UV-A130-CE275-00

www.led-tech.de

Since the forward currency changes the output I wonder what would be a reasonable setting to run 4-8 of them in a 1.44^2 tent?

edit:
BTW I mixed up mA with mW - sorry

 

[nunyabidness420]

so is this sheet in error?

Luminus XBT UV 275nm-285nm auf 20mm Star - XBT-3535-UV-A130-CE275-00

www.led-tech.de

Since the forward currency changes the output I wonder what would be a reasonable setting to run 4-8 of them in a 1.44^2 tent?

Yeah they're suppose to look like this.


I'm driving my UV leds with a 350ma constant current driver.

 

[nunyabidness420]

I'm definitely increasing my wattage when I switch to a 3x3 grow.
10 of these running at 350ma each will get me 350mw UVB.
About the same as the Agricultra light.
Not sure if I want to run the UVA on the same driver though.

 

[Rocket Soul]

As for uvb i refer mostly to @nachooo s work, he does 60mW total of uvb output (peak nm 285) from 4 points of light at around 30cm/12" height over 1m2 for midday up to 3 hours. This gave both noticeably stronger high and new terp profile. 350mW of led output seems like alot, its extremely easy to burn your crop with uv, especially borderline uvb/uvc.

It would be awesome to see some tests of sunlight grown weed of the above mentioned genetics for contrast. My mate gave me some outdoor bud grown of our elite cut and it was miles more stony than what our white led and cmh grown bud.

 

[nunyabidness420]

350mW of led output seems like alot, its extremely easy to burn your crop with uv

I'm starting to think they can take quite a lot of UVB once they acclimatize.
Worst case I can pulse the UVB portion throughout the day.

 

[Rocket Soul]

I'm starting to think they can take quite a lot of UVB once they acclimatize.
Worst case I can pulse the UVB portion throughout the day.

Try it out and let us know make sure you spread that uvb properly. Watch out for signs of uv burning: light green color with the serrated edges of the leaves "tacoing" or turning upwards.
Too much uvb will decrease your yield drastically.

Be aware that your proposing 6 times as much uvb as nachoo uses and he knows how to grow very well, same sativa cuts since a long time and several goes trying to push as things as far as he can.

 

[nunyabidness420]

light green color with the serrated edges of the leaves "tacoing" or turning upwards.

That's not a UV burn.
This is a UV burn.

 

[Kassiopeija]

That's not a UV burn.
This is a UV burn.

 

[Kassiopeija]

btw the datasheet has it the differences between low/top bins are around ~60%

and no life expectancy given... ("contact us")

 

[ttystikk]

a well known grower here is using 5000k led flood lights with UV bulbs and a 450nm led strip light View attachment 4685706very little red. did you find any evidence that UV or violet promoted flowering?

That's @RM3's grow. He will be happy to discuss it.

 

[ttystikk]

Well my opinion is the "optimal" amount will vary among strains and will also depend on the ratio to other colours, as well as the initial UV wavelength. No to mention how long you expose the plants.

Sunlight is about 3% UV. Of this, UVB accounts for 5% and UVA 95%. But that total ratio (3%) is when the sun is at its highest at the equator at sea level. Total UV can be much less than this depending on the time of day, season, equatorial latitude, altitude, ozone layer etc.

I believe these points have been covered elsewhere in this thread (or possibly the other UV thread), but what it means is that improvements can be seen with very little UV – and indeed studies have shown that increases in cannabinoids can also be achieved with violet (near-UV) and blue light.

The Italian studies as well as the Or_Gro tests seem to suggest that additional blue light can also increase cannabinoids in the presence of UV. That makes sense when you think about it, because blue light is higher energy light compared to other visible colours. So if the secret is to mildly stress the plant to produce more cannabinoids, then it stands to reason that you should be able to achieve this with smaller amounts of blue light than, say, red light.

In the mean time, all we can do is experiment to see what works.

Right, and that's where my question about optimal levels comes in.

What I'm hearing is that people are still working on firm answers and that's okay.

I read the old study that discussed the efficacy of UVB without much in the way of charts. From reading these threads (thanks for the link, btw), it seems that UVA is important in the mix as well.

More experimenting is needed!

 

[Rocket Soul]

That's not a UV burn.
This is a UV burn.
View attachment 4686005View attachment 4686006

What was the conditions on this? How much exposure of what? I happily admit i havent tried uv supplementation myself but everytime ive seen it overdone online its been quite a lot more light in color.

 

[nunyabidness420]

btw the datasheet has it the differences between low/top bins are around ~60%

and no life expectancy given... ("contact us")

I've only seen the CC and CD bin for sale.
I've got the CD bin.
UV LED life cycles are suppose to vary according to drive current more than white LEDs.
Heat also plays a large part in it.
Good thing I picked up extras.

What was the conditions on this? How much exposure of what? I happily admit i havent tried uv supplementation myself but everytime ive seen it overdone online its been quite a lot more light in color.

The first pic was from the first time I ran this.


The middle LED is the XST, older model 275nm, paired with 2x 365m, and 2x 395nm.
I didn't have the correct mcpcb then so it's kinda messy.
The XST is a 60 degree beam and it roasted the bud that was directly underneath it.
It was also sitting way too close to the LEDs.
I don't remember how long I had it on but I don't think it was for more than an hour.
I was using reptile lights before that and didn't realize how much more power these have.

The second pic was when I forgot to turn the UV off after manually exposing the plant.
I think it had acclimatized to UV already so it wasn't as seriously burned.
The module was also further away.
I think that was a couple hours more than normal exposure.
If you look at the leaf on the right you can see the shape of the top leaf where it blocked the UV.

 

[nunyabidness420]

everytime ive seen it overdone online its been quite a lot more light in color.

Maybe mine is a burn and the lighter colored ones is closer to photobleaching.
Was it like this?

 

[Warpedpassage]

From the pdf randomblame posted recently , uvb led being discussed. I think this is roughly 5mw per square foot, about a 1ft away. 4 hour exposure for the last 4-5wks of flower. Hot damn look at the increse in the terps.
This also shows what people have been saying for years in reference to quality of flower being superior under led than Hps.

 

[mauricem00]

That's @RM3's grow. He will be happy to discuss it.

i learned a lot about growing with t5s from him.i respect his knowledge.

 

[mistergrafik]

From the pdf randomblame posted recently , uvb led being discussed. I think this is roughly 5mw per square foot, about a 1ft away. 4 hour exposure for the last 4-5wks of flower. Hot damn look at the increse in the terps.
This also shows what people have been saying for years in reference to quality of flower being superior under led than Hps.
View attachment 4686181View attachment 4686182

So this promotes that UVB is more essential than UVA? is this correct?

 

[Warpedpassage]

So this promotes that UVB is more essential than UVA? is this correct?

I dont think it’s necessarily essential. hps growers get amazing flowers without any uva or Uvb. However it will give you an extra edge in terms of overall quality by increasing terps and even some cannabinoids. But it wont make trash genetics into gold. Having said that, members here postulate with good reason that near uva 410-420nm also increase terps and cannabinoids.
In conclusion i would suggest if you have everything else including your dry and cure on point, as well as working with quality genetics and can afford to play with the uvb, go for it. But in general i would recommend the boards from growlightaustralia since they already have the near uva integrated into the boards and get nothing but great reviews from everyone that tries them. If i was in the market for leds, i would not hestitate to grab their new boards that in addition to the near uva/violet offer an amazing spectrum with a very , very nice deep red peak.

 

[Kassiopeija]

There is a meta-analysis on UVB & Cannabis, and it clearly proofs increased THC content. Now, keep in mind that this kind of radiation is absorbed quickly by biomatter, so UV doesn't illuminate the whole plant - but the destructive effects of UVB only apply on direct exposure. So what I'm saying is that what Lydon (et al) found could be maximized further with proper/clever outlighting.