My area is about the same as yours (2'd x 4'w x 6'h), and I use one 400 watt light (with a digital ballast to minimize heat), and I also use two sets of four 30-watt CFLs at the far ends of the rectangle to provide additional light to the plants more distant from the 'sweet spot' right beneath the HPS light. Two 400s would probably be better in terms of lumens/plant, but that might also be somewhat of a heat problem too, I dunno. In any case, my lighting seems to kick serious ass for that area, and the heat is manageable, even on these 97 degree days. If I were you, I'd try the same thing: start with a 400 and some sidelighting CFLs and see how your temps are. If they're totally fine, zero probs, then it might be worth trying a second 400. (If you can do it, two 400s would be better than one 600, not just because of the extra lumens, but also because you can get a better spread on your lighting, and because you have lighting redundancy in case a light fails.)
jamstigator Reviewed by jamstigator on . How big of light should I use? My space is 5ft Height x 5ft Wide x 1.5 deep. Roughly about 20 sq ft is what a website told me when I typed in my measurements. I was going to get an aircooled 1000MH/HPS switchable for this but I was thinking this just might be too powerful and too much light for the space. I have about $300 to spend on the light and with that I can go a little over (indeed I can afford the light). Ongoing however I'm thinking with the extra light it may or maynot payoff for my SOGGin' in this closet .. Rating: 5