Ok so thought I would go over uva and uvb supplemental lighting, first of all anyone who is looking to buy supplemental uv, a or b , know what you are buying and how much you need per sq ft to be effective. Led lights with built in UVA lighting ( not seperate supplemental bars) are worthless, they are usually 395 or 400 nm , not to say that's not a good spectrum , there is just not enough diodes to do anything beneficial. For UVA look for a mix of 365 and 395 or 400nm. These are not easy to find, I had to order mine from China, could have easily gotten 395nm from Amazon but the 365 is where uva secondary metabolites shine. Also you need at least 3 watts per square ft of UVA. So a 4x4 would need 48 watts of Uva . UVA will not increase THC or defensive trichome production. It will however , in sufficient supply increase secondary metabolites, hence terpenes. Uvb is a different animal, it is where you run into stress related trichome production, leading to increased THC. It is also the quickest way to fry your plants. Look for 285 to 310nm spectrum. Led uvb are not good yet, they lack the technology necessary to produce consistent light under 310nm, even the newest from Mammoth, which arguably is the best company for cutting edge led cannabis lighting technology that claim true uvb spectrum are sketchy. Look for t5 ho 54 watt flourescents 41 inch bulbs. The bulbs are made for reptiles and come in assorted strengths from 3 percent uvb to 14 percent uvb. They are all real uvb spectrum consistently in the 285 to 300nm range. Agromax has a pure uv t5 bulb which is 75 percent uvb and 25 percent uva, but thats the mix percentage of the bulbs they don't mention the actual uvb percentage based on total watts, same as the migro bulbs. I own them now and am hoping that with 54 total watts that its 40 watts uvb and 14 watts 395 uva. I also have 2 t5 14 percent uvb dragon lights that are also 54 watts and of course have 7.5 watts of uvb per bulb. In difference to uva, with uvb it is necessary to have .3 to a half watt per sq ft. for prime efficacy. The problem with the uvb fixtures are they are usually only used as 1 light per 4x4 or 5x5 in the middle of the primary led light, this creates uneven coverage unless your manually moving every two to three days in different parts of the canopy. I spent a lot of money on uva and b, but only after many hours of research. Also Uvb should only be used during "high noon " scheduling for 2 hrs max the last 2 or 3 weeks of flower. I am using 4 54 watt t5 per table (9x4.5) and (10x4.5) so 8 lights total for both beds at a pulse schedule ,30 min on and 1.5 hr off schedule starting at 1 hr total uvb time for week 7 and finishing at 2 hrs total time week 8 or 9.I think for the money there are a lot better things to buy than UV, such as a/c , dehumidifiers, quality fans and other equipment to get your environmental vpd , dew point, and air flow in check. And of course the cheapest and most beneficial attribute you can buy CO2. I wont grow without it!!
