...according to my calculations (Calculator, that comes to 675 cubic feet. I will be having 2 - 600w HPS lights. I already have an 8,000 BTU AC Window unit at one end of the room which is keeping the room more than cool right now, although I only have one of the lamp hooked up at the moment. What kind of fan do I need? I plan on using a carbon filter for the smell and just running ducting through a tarp that is dividing the room. Im not quite sure how fans work (inline im assuming I need), but I'm wanting to have the carbon filter on one end of the fan and ducting on the other...is this how these fans work? And last, what size carbon filter do I need?

Thanks to everyone!

Peace

Take your 675 cf and divide by 5 = 135 cfm. Thats the size fan you'll need for odor control. In your setup you really don't need ducting if you're going to recirculate the treated air. Remember, you only need to filter the girls that are flowering. A free standing setup will do that nicely. BTW, it sounds like you have nothing currently ducting outside...correct ?

[SIZE="3"][B]Here is the link to Phesh filters... It has a formula for sizing includedPhresh Filter Carbon Filter RC 48 Australian Activated Carbon

No current ducting, but dont i need ducting to filter the air out of the room?

Do you need a fresh air makeup ? YEP... Does that involve ducting... maybe. You do need to get fresh air through the room and maybe you're getting it in already... For exhausting, you have an option of going up or out with a exhaust. Mostly I'd say that depends on what season you're in. But, the air has been treated for odor so, you can dump it wherever you want...

Sweet man, I checked out that website, punched in my dimensions...I think I should be good with a 449 CFM fan. The fresh air is actually coming in through a window, a/c unit. Its blowing cold though! 8,000 BTU's! I can adjust the temp on the a/c, right now its at 70 F, which is making the canopy around 81 F ( a bit higher than i'd like)
I finally got a hold of a digital camera, here are some pics:

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My idea is to put the carbon filter/inline fan at the opposite room from the a/c unit. I would think this would create a good airflow if i ran duct through the other end of fan and out through the tarp into the next room.

Any thoughts?

I appreciate your help, thanks