How close to the plant are you talking about? I'm leaning more to the procylon, I would buy two of them for dark room 60, 2 feet by 2 feet with about 55 inches high. I was thinking of placing them 8-12 inches about the plants. As far as leaf penetration I wouldn't prune but tie leafs down and such. Lowryder 2 # was my plan and yes 24 hours makes sense. Anyways I heard the UFO's are crap... something about procylon being better. So how close to prevent strechting, and are you sure you bought an up to date ufo and not some outdated garbage. Cause people do that... any advice you think that I should know just suggest it at random.