Oldmac it's not the uv-b that is making your plants rippin faster it's the blue light associated with the uv bulb you are using. Let me explain.

Most of the cfl type of uv bulbs from (pet stores) omit in the low 300nm to about 400nm BLUE range. That low blue nm range has a fast Time Factor associated with it. So when you add let's say 3 hours of that fast blue nm light to your existing 12 hours of day light you are actually lowering your lights overall 12 hour Time Factor. If your current combined lights Time Factor was say at 4 (just an example) before you added the 3 hours of the fast 300nm to 400nm blue to the mix, now your lights overall 12 hour Time Factor will be around 3.8 ish or lower (just an example) but you get the point. The faster Time Factor day after day will speed up the flowering over time. The truth is.... Speed is one of the only good thing those bulbs offer and it's actually just the Blue 300nm to 400nm that has the speed. Also it's the blue spectrum that makes the leafs,stalks thicker not the uv-b. If you remove the uv from those bulbs and just use them as speed and a blue light source then they are ok. But if your using led's and T5's as your light source then chances are you don't want the thicker leaves because of light penetration issues. Light penetration issues will cause lower THC production by default. So the less blue the better if you don't want to produce thick leaves. IMO

Personally I get most of my speed from far red. Far red has the fastest Time Factor for plants but gives no useful bulk and will cause stretch in the early part of flowering. The strain I work with only likes the low fast Blue nm in the first two weeks of flowering and I like to use 420nm. Not much uv in these lights but good speed.. Any longer then two weeks and the added blue starts to make the flowers way too leafy for me.... But the blue helps keeps the early flowering stretch down and the speed up (red 630nm to 660nm will also keep strech down BUT the speed (time factor) is to slooooow for me)...

My point is.... When everyone figures out that speed (300nm to 400nm) is the only thing good about these lights. The next step will be seeing that the good (speed) don't out way the bad (uv-b). There are much better ways of getting the plants clock moving faster IMO.

More to come soon. :thumbsup: