im pretty sure how watts dont have anything todo with the amount a fan will cool, the "cfm" you mentioned is cubic feet per meter. fans cfm's are measures in how much air it will move. not sure about the other question. as far as how far, cfls burn really cool. unless your being very careless you wont start a fire with them being too close to a hood. you can literally put them 1-2 inches from the top of plants with a fan and not burn them. hope this helps a bit. goodluck
It's cubic feet per minute. Not meter.
To answer the original question. If you are using a bought carbon filter, no pc fan will work with it. If you are using a carbon filter you made, next to no pc fan will push air through it. The rated cfm and the actual cfm are completely different ball games once you throw on some resistance, meaning you put a filter infront of it. cfm is dramatically reduced. With PC fans, often it's 0 or close to it. I bought 2 tornado pc fans rated at something like 150cfm once I put a carbon filter pad on them, hardly an air came through. They just don't have the torque required to continually push the air through them. cfm is rated with 0 resistance.
On my first grow, I built a grow box out of particle board and had cfls basically touching the board all day long. Never had a fire. I even painted the wood white.
