cooling issue

ok i know people here want all the facts when asked a question so here it goes. I have a 16 cubic foot cabinet with an 80 CFM fan going through a carbon scrubber. Would this be enough to cool a 400w hps or should i go 250?

the fan you have is fine for your exhaust. if you use a separate fan to air-cool your light, you may be able to keep it cool enough.