Air cooled hood change necessary cfm?

I have an air cooled 600w hps hood that has a hookup for an exhaust fan. My room is 5x4x6. (120 cu. ft.) i figured that this would help to remove some of the heat directly from the light/hood. I still want another exhaust fan just to keep good ventilation in the room itself. i was originally looking to get around a 450cfm 6" fan for the room and a cheaper 200 cfm fan for the hood/light. since the hood's fan will be pulling some of the heat out already, do i need less cfm for the room's exhaust fan? thanks

That's sounds about right. I use even less venting 2 1000w lights. So you will be good. Your higher output fan should have a Carbon filter too for smells. You should have plenty of cfm. I'm using two in line duct booster fans and still no heat issues but I use a box fan tooN you can probably just get two 200cfm fans

i dont think you even need that much ... i use a 420 cfm can fan thats pulls from a carbon filter through the 1000watt hood and into the attic with a 180 cfm intake fan and my temps never get about what the house stay at .. sometime they even dip into the 60's with the light on

Hey, thought I would chime in as well. If your keeping one end of your hood open to pull air across the bulb and out of your space then 400cfm should work nicely! I use a 460cfm 6'' ecoplus centrifugal fan to extract the air from my cab over the bulb (400w)then push thru the DIY carbon filter I made.I was trying for a passive air system. The speed control I bought was 23 bucks and I cannot recommend living without one. Starting with a setup like your talking about might save you from having a box or two of misc fans and junk that you later didn't need (I throw nothing away!). I was able to unhook some intake fans because my fan was big enough. I later added another light that wasn't air cooled and it was cheap with the ballast attached so it raised temps but the fan was big enough to regulate the heat. Happy Growing!

here's a handy tip: to keep your hood glass clean from dust, insects, slip an air filter over the intake end of the hood ... WalMart, Home Depot, etc., sell a round air-filter to fit their shop vacuums ... it fits a 6" duct perfectly, its about 8-10" in diameter, has a rubber lip around its edge, that holds itself in position, usually not even needing a clamp ... cheap, too, I think I paid about $10 for mine ... never seems to need replacing, because grow cabinets are clean (or, should be ;) ) ...