How much uvb is too much??

McCheeze

McCheeze

Member
Like the title says. I know there must be a way to calculate what is optimal or should I just say screw it and go with 25% of the lights uvb?
 
rkymtnman

rkymtnman

Well-Known Member
i use 2 23w 10.0 uvb cfls in a 3x4 space. plus whatever uvb my cmh bulb kicks out.

i'm not sure if i ever saw a formula to calculate how much uvb is too much or too little
 
testiclees

testiclees

Well-Known Member
I think there is a UVB thread by kitehigh. It shows a calculation and suggests the best bulbs.

I use a 54w t5 which is 12% uvb in my 10ft sq garden. It's a 48" reptile bulb.
 
rkymtnman

rkymtnman

Well-Known Member
testiclees said:
I think there is a UVB thread by kitehigh. It shows a calculation and suggests the best bulbs.

I use a 54w t5 which is 12% uvb in my 10ft sq garden. It's a 48" reptile bulb.
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what is the effective range of the t5 style? the cfl style is about 20inches. we are both about the same wattage and sq foot wise.
 
McCheeze

McCheeze

Member
I've got roughly 5sq ft wardrobe cab using 200 watts of diy led and would like to add uvb just don't know how much to add or if its possible to add too much
 
testiclees

testiclees

Well-Known Member
rkymtnman said:
what is the effective range of the t5 style? the cfl style is about 20inches. we are both about the same wattage and sq foot wise.
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im not 100% on that. I'm working with the assumption that 12-18" is good. I run my tube straight down the middle of the 50" length. It ranges 12-20 " over my uneven canopy. I turn the plants from time to time to even it out a lil bit.

For a single row of plants it may be better to mount it on the side so it hits more than the tops. Seems like rotating the plants around the tube would give a lot more coverage vs hanging it on top
 
nomofatum

nomofatum

Well-Known Member
About 5w of 10.0/9.9% UVB bulbs (tanning or reptile) per square foot will put you in about the same range as the hindu kush mountains (UV index of 12). I'm running 6.5w per sqft and it does not appear to be too much.
 
nomofatum

nomofatum

Well-Known Member
What are the dimensions? Those are likely less efficient, and remember you need to get replacement bulbs every 800-1200 hours generally. In that small of a space you are likely looking at 1 or 2 T5 tubes or 1 or 2 CFLs.

I hope your walls are mylar and not white. bongsmilie
 
McCheeze

McCheeze

Member
My cab is 18in deep 36wide and 54 high that's in inches by the way if you have to change them every 800 to 1200 hrs that means every new grow will need new bulbs right?
 
nomofatum

nomofatum

Well-Known Member
McCheeze said:
My cab is 18in deep 36wide and 54 high that's in inches by the way if you have to change them every 800 to 1200 hrs that means every new grow will need new bulbs right?
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UVB output will drop by 20% around 1200 hours in. You have to decide if you want to run them the full light cycle or just during the "noon" period. Outdoors UVB is much higher when the sun is near it's peak. If you run that way you can get 2 grows in.

2 of the CFL versions will probably be easiest in that space.
 
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