I'd like to know, too. However, I've read a little and shopped some, but I've come to believe that the less expensive 3000K for flower and 6500K for veg will be fine. I'm no expert in this regard but I'm a willing learner. I'm only doing the lights for seedlings and starts, though. I'm an outdoor grower in dirt, but I'm starting to think about a full indoor grow. As with any hobby, one can spend as much as they want. I'm frugal (cheap), that's why I go with T5's.(I haven't grown under lights for 25 years). I have a 2'x12 lamp grow light in a 3'x3' tent, though I don't need the full 12 lamps, I might take something to full bloom sometime, when I will want them. This helps alleviate the "post partum blues" I get after harvest in October. I grow much more than cannabis.