hey kgb..as long as you can keep it cool, 1000 watt hps is great. They do produce alot of heat, so your probably loosing about 16" in ceiling height, unless you use a cool tube. I use a 1000 watter in a 8'x8'x4' tall space (really the 8x8 is meaningless, except for airflow, because at 4' off the...