I'm a total noob but here is what I have, 36?x20?x64? grow tent with an htg 250w hps with cool tube hood. I have one 6" high output fan for intake into the tent, One 4" inline fan sucking air through the cool tube and one 4" inline for overall exhaust and both of these t'd into a filter. I run between 76 and 79 degrees all day long with the room temp at 69-70 degrees. I have seen excellerated growth since switching to hps and the exhaust upgrade as compared to my 2ft 6 lamp 3veg and 3 growth bulbs and just the 4" inline fans. I hope this helps.