Any UVB'ers out there?

[Blazer420]

I have been using some UVB for the first time in the grow journal in my sig line below. So far things are pretty interesting.

That said, I have been doing some research into UVB and cannabis growing and came across this video where I cut it at the point where he talks about UVB.

I highly encourage watching the video from the beginning but if you are interested in UVB the previous link will take you there.

I would like to start a discussion about UVB, how it works, what lamps are best, etc. If you have any experience with this, please chime in. I'm only at the learning phase with UVB and would love to hear what you all have to say.

Thanks!

B-

 

[The303Stoner]

UVB You know me Damn skippy I'm wit it!

 

[The303Stoner]

that was a cool vid

 

[Blazer420]

Yea, I thought so too - especially if you watch the whole part and he completely dissects the trichome and what it does.

B-

 

[Blazer420]

You know, the more I read and research cannabis growing and UVB it sure dawns on me that simply adding a few UVB CFL's or fluorescent tubes to a grow makes a lot of sense.

1) It sure seems cost effective
2) Actual science proving its benefit
3) No added chemicals to a grow

The list goes on and on.

Why don't more people do this?

B-

 

[Richard Richardson]

I do this I have 600W HPS, 125W 6500K CFL, Various 30W CFLs

and a 30W T8 Reptile 10% UVB tube, which I switch on or off each visit to simulate cloud cover.

 

[The303Stoner]

I have a digital 400w ballast I switch a HPS, a blue MH which has a bit of UV and deep red, and a 10k sunpluse UVB MH down side $120 the plus side only needed part of the grow. I also use grow Cfls which are full spectrum meaning they have full spectrum but in different ratios even some amounts of UVB. I know you shouldn't but watching the first seconds of Blue MH gas warming up is amazing.

 

[Paonia Purple]

Interesting video to be sure. I wonder where he got the figure of 270-300nm for the uvb that is most useful to cannabis? High pressure mercury lamps have a goodly amount of emission in that range (particularly at 253 and 313 nm).

A DIY approach would be to break the outer envelope of a low power (75 watt) mercury vapor lamp and jumper over the safety shunt. The outer envelope is designed to absorb UV, but the inner quartz capsule is transparent into the UVC range.

I made a short wave UV lamp exactly this way for mineralogy use. I had to add a visible light filter to get rid of the red and green portions of the Hg spectrum, but for plant use, the above idea should make plenty of UVB in a beneficial range. I'd want to start with short exposures, as this type of lamp will make lots of uv, and some ozone as well. Skin and eye protection is highly desirable around this kind of high power UV source, too.

I may have to take the lamp I made and add it to my grow cabinet...

 

[The303Stoner]

Breaking a bulb is not the best Idea. Removing the hood glass on a blue light should work allowing the uv light to reach the plant.

 

[Paonia Purple]

I did some research yesterday on UV strength at various elevations. There's a pretty good simulator at
FASTRT-UV dose and irradiance simulations

A starting point for deciding how much UVB to use would be fairly easy to find. I got the following result

FASTRT ver. 2 main inputs:
Solar zenith angle = 60.00 degrees
Julian Day = 81
Sky condition = Cloudless
Visibility = 25
Total ozone column = 350.00 DU
Surface altitude = 0.15 km
Surface albedo = 0.03
Triangular spectral response function = 0.60 nm FWHM
Results:
wavelength (nm) surface irradiance (mW/(m2 nm)) mW/m2

290.00 2.765e-10 8.0e-8
291.00 1.107e-07 3.2e-5
292.00 3.209e-06 9.3e-4
293.00 2.130e-05 .006
294.00 7.785e-05 .023
295.00 3.189e-04 .094
296.00 1.589e-03 .471
297.00 4.026e-03 1.197
298.00 1.570e-02 4.678
299.00 4.280e-02 12.79
300.00 8.946e-02 26.85

total irradiance is about 46 mW/m2

If I use a 1 watt source on 2 square meters of plants, I'd get 500 mW/m2, or about ten times the average sea level irradiance. I wonder how much UVB the 'reptile lights' put out?

 

[David Bowman]

In terms of wattage, 20% of the lighting I use during flowering is comprised of 10% UVB CFL bulbs. The plants did not appear to have any issues, the only issues I had were some bleaching/discoloration of some of the plastics in the grow box and due to the quantity of UVB present I found that it was a good idea to wear sunglasses while working on my ladies.

 

[Bigbudbill]

Please friend, consider shutting the lights down while your working. Your eyes are only a small part of what's affected. Consider your head, neck, arms and hands as well. Often when working on things, you end up MUCH closer than your plants. We're talking about intentionally focused use of all sorts of radiation. We really don't have a lot of information about close proximity to some of these new tech. lighting, especially over time at high concentrations. Besides, it's much easier to spot deficiencies etc. under more "normal" lighting. After a quick inspection that all your lighting is working up to par (pun intended) shut it down while your present.

 

[David Bowman]

I do turn off the UVB lights if I going to be working on the ladies for an extended period of time. I use the sunglasses when I'm doing a quick check or some simple task that only takes a minute or two. I only have a 2'x4'x5' grow box so I'm never fully surrounded by the lights and when I'm not attending to my ladies, it stays closed so no light can escape.

 

[The303Stoner]

Wow I need to bust out the dictionary just to get a clue on understanding Paonia Purple's post

 

[Blazer420]

I feel the same way.

I still don't have a clear picture why the use of UVB isn't more widespread though... Just doesn't make sense to me. Everyone is willing to jump on some "new" nutrient or training regimen, but hanging a couple of reptile UVB bulbs is not even on their radar.

B-

 

[Paonia Purple]

Lol, sorry if I got too technical. I'm a science geek from way back, and an engineer nowadays.

If I read the numbers right, ColoHigh's mix has about 2% UVB. Natural sunlight has about .005% UVB (again, if my numbers are right) So he has 400 times as much UVB. I can see why plastics would bleach out a bit. :O

Blazer- i love the line in your sig "Avoid the temptation to do something all the time with your plants. Not touching them is actually doing something." Fits me to a tee- I'd be fiddling with them all the freakin time if I didn't know better...

I have an old blacklight, but I suspect it's mainly UVA. I don't know of any easy way to measure the UVB content without a $$$$spectrophotometer...

My buddy just harvested his Maui plants and gave me some buds. Loose and fluffy, but oh my do they smell good!!

 

[think difrent]

Please friend, consider shutting the lights down while your working. Your eyes are only a small part of what's affected. Consider your head, neck, arms and hands as well. Often when working on things, you end up MUCH closer than your plants. We're talking about intentionally focused use of all sorts of radiation. We really don't have a lot of information about close proximity to some of these new tech. lighting, especially over time at high concentrations. Besides, it's much easier to spot deficiencies etc. under more "normal" lighting. After a quick inspection that all your lighting is working up to par (pun intended) shut it down while your present.

man are you not worried that your plant wil turn hearmi? how dos this work shuting off the lihgt during the day do you hawe an other low watege bulb that you turn on or what ? i red that many thimes but newer understud it
in the midle of the day my dan not the plants day haha wird a if i shut off the lights my tent is dark i cant see noting REALY SORY FOR MY EANGLIS
we are all constantly learning peace

 

[David Bowman]

The UVB CFLs I use during flowering are part of the sidelighting I employ during my grow. The majority of my lighting comes from 2-125 watt CFLs hanging over the canopy and I leave those on during any extended work where the sidelighting has been turned off. BTW, a lack of light during lights on is not nearly as bad as having any light during lights out.

 

[Bigbudbill]

man are you not worried that your plant wil turn hearmi? how dos this work shuting off the lihgt during the day do you hawe an other low watege bulb that you turn on or what ? i red that many thimes but newer understud it
in the midle of the day my dan not the plants day haha wird a if i shut off the lights my tent is dark i cant see noting REALY SORY FOR MY EANGLIS
we are all constantly learning peace

Sorry, I should have been more clear. Kill the UVB source (whatever yours may be) and work under a cfl, fluorescent, standard bulb or whatever. Your plants are far less likely to go hermie from an interruption in their day cycle ie going from light to dark as opposed to interrupting the dark cycle (at least in my experience with Sensi Star). Besides, I can "read" my plants better in lighting suited to my eyes as opposed to trying to see what's going on in an oddly colored LED, or glaringly yellow hps. You'll spot subtle changes BEFORE they become serious deficiencys.

Sensi Star was a learning experience. Great yield, awesome high, little smell during the grow. But any little stress (heat, nute burn, light stress) sent it to banana land.

 

[dawill1967]

The CLW LEDs have two built in 15W 10.0 bulbs. That's what I use.