ho many wats?

Haya my growing room is a 15ft/sq and i will grow 40 plant how many wats HPS lamp i need?and the ventilations sistem is a nececery?or only FAN? tanks

If it's a square area, a 400w hps is minimum, but a 600 would be better. Yes you are going to need to vent that heat somehow. And no, going cfl won't help with the heat, that grow is too big for them anyway.

40 plants? What are you growing a zero veg sog? Even still that's a lot.

i Have 3x400HPS and wanna buy 1x200 or 400 MHl its a good?MHl for the start and after 5 wks will turn the HPS's.....but the problem is a ventilation system...its so expensive....