Whats up fellow growers I have a quick question my grow room is 30in by 24in I currently am running cfls I wanna switch to hps my question is 600 overkill the reason is because I found a 400 then found a 600 for 20 bucks more heat is really not an issue but how much hotter does a 600 run than a 400
I run a 250w hps on a digital ballast in a 2'x2' grow tent...you could always get the 600w hps if you feel like someday you may have more space or something, you can buy a lamp/ballast combo that lets you dim yorr light to 400w if you have a 600w system...my dimmable ballast lets me go as high as "250w super lumens" (more lumens output) or as low as "150watts".
What is the height? 400w is enough, 250w may be all you can use without heat problems though. Don't forget to add ventilation fans if you haven't already... outtake and oscillating fans