Lighting UV Lights

[ThaGreenBandit]

I've been doing some reading on UV lighting, and some of the info opinions on its usefulness vary greatly. So, as always do, in the end, I come to my AFN fam for the final say. What say you, AFN? When is the best time to supplement with UV lights? The final 2-3 weeks of flowering, after the first couple weeks of veg, or at the very start of flowering? How many hours a day should I run the lights? I've read 1-2 hours tops. I've also read that we should mimic the hours of the sun. I don't know! Does UV light even really lead to more trichs and more resin?! Thanks in advance for the input, guys and gals

 

[Weedman30]

Id recommend using UV the last two hours of lights on approx 12-15inches above canopy i have a 26w bulb i used in a 5x5x7ft it helped but i also belive a mixture of 6500k and 2700k cfls will help produce Trich production with Leds as well

I only added the UV last 2-3 weeks as with CFLs i leave from start to end.

Oh and dont look at tbe UV bulb i wouldn't even recemmond opening the tent when its on.

 

[ThaGreenBandit]

Thanks for the input, Weedman. I'll be using my 26w light in conjunction with my 400w LED panel. Did you notice any apparent increase in trichs?

 

[1guy1plant]

That has been my question. I received my 26 watt UVB light today. I have been running 8 mixed spectrum cfls with my LEDs the entire grow. Are the cfls enough UVB light or do I need to drop the UVB bulb in a few hours a day as well?

 

[ThaGreenBandit]

Good question, 1guy. I'm sure we'll get some good responses

 

[Dr. Frog]

If you search "CFL UV", you'll find lots of current articles addressing consumer health concerns related to UV exposure from ordinary CFL bulbs.

CFL's use electrical energy to excite mercury and argon gases into making UV light. The white light we see is actually the fluorescence of the phosphor doping or coating on the inside surface of the glass as it reacts to the UV.

By design, the phosphor coating on the inside of the bulb is meant to block the UV light. However, due to the tight coil shape of CFL's, the brittle phosphor is prone to cracking or flaking off (I've noticed old/worn CFL's with cracking or little specs rattling inside the tubes). Through these cracks, UV light escapes.

So all CFL's have the potential to supplement UV light, depending on how their phosphor coating deteriorates with time. It's just difficult to determine how much any one bulb emits without a meter (or even which *kind* of UV).


In my personal experience... I recently had two autos growing in the worst possible soil. I had practically abandoned them. I cast them out of the tent and into a closet with just 2 of my usual CFL's. They struggled and remained small, but they produced the most resin of any of my plants so far. One plant was Think Different, which I've grown three times. This crappy CFL closet grow gave me the most potent TD I've had yet. So idk if it was the crappy conditions, or just 24 hour CFL with inherent UV leaks that did it... I sure didn't try hard.

I feel certain that putting CFL's in good reflectors will definitely give you some UV, depending on the age/condition of the bulb.

My new smartphone has a UV sensor. Maybe I'll be able to do a few tests for AFN.

Anyway, here's a good read on the subject.

http://ehp.niehs.nih.gov/120-a387/

It's centered on human health, but you can see that UV from CFL lighting IS a thing.

HTH

 

[ThaGreenBandit]

Damn, Doc, you always got something good to say! That UV sensor, is that an app?

 

[Dr. Frog]

Damn, Doc, you always got something good to say! That UV sensor, is that an app?

It's a new sensor on the Samsung Note 4. I almost forgot it even had it.
It's a part of their health app, meant to measure the sun's UV and how "safe" it is. Not very useful, but hopefully I can find an app that gives numeric readouts for the sensor.

Here's a screenshot of the UV from the Christmas tree... nice and safe

Gotta wait a bit to test my tent out.

 

[ThaGreenBandit]

Now I gotta find an app! I still use that light sensor app you turned me onto! Just threw a 26w UVB bulb in my grow cab, and I plan to run it about 2 hours a day for these final 3 weeks. Think it'll pump up the resin, or need more watts?

 

[Dr. Frog]

Now I gotta find an app! I still use that light sensor app you turned me onto! Just threw a 26w UVB bulb in my grow cab, and I plan to run it about 2 hours a day for these final 3 weeks. Think it'll pump up the resin, or need more watts?

Honestly, I have no idea. I haven't seen any studies on the matter, just a bunch of anecdotal evidence. That, plus my unscientific findings on my own plants. (does anybody have any solid info on this?)

I believe it helps, but UV can be pretty damaging to life. A little helps, too much damages... after reading that article, I'm thinking sunglasses in my tent would be smart. No telling how much UV my old CFLs may be leaking! :X

I guess a reasonable approach would be to look up solar UV levels in regions known for potent outdoor crops, and use that as a ballpark amount. Can't say whether that's optimal or not, but at least it's how nature does it.

I wish I had the grow space to do science! Lol