3x3 tent 400 watt hps cooltube 440 cfm fan plugged into a fan speed controller (on low all the time) Also what cfm is my fan running when it's on low??
Pretty sure you would have to check the specs of the fan in the manual or give the company a call and ask. Don't think there would be any concrete answer as a lot of variables would play into how the CFM would change at certain speeds. Im sure they could give you a "ballpark answer" though.
I got my at the grow store and the chic had a formula you put your dimensions of the room in and it tells you proper size. Go the the grow shop and ask. You don't have to buy it there.
It's a 3x3 area 440 is over kill that's why I use the fan speed controller and keep it dialed down all the way. I'm wondering what speed to keep it at if I get a carbon filter rated at 440 CFM. I think full speed with the carbon filter in a 3x3 tent would be too much