I can get my flouro setup up to 2 feet away from the tops and still have mad growth. heres what I use....... a 4 bulb teklight t5 with 2 2x overdriven 2 bulb electronic ballast t8 shoplights hung from eack side of teklight. all bulbs are 6500k spectrum. but thats just for vegging, for flower I use a 1000 watt hps lamp with a hortilux bulb.