Fan Size
 

How many cfm would be required roughly for a 4' tank with (2) 250w halides in a mostly sealed hood.

i have a 5' 105gal tank in my basement, I have a 120mm fan on each end of my canopy, 1 blowing air in, 1 sucking air out. When I run the fans at full speed, my tank temp goes down, even with the halides on..so I turned them down to 9v instead of 12v. I'm not sure what the cfm is now, but full speed is around 86cfm.

I was thinking around a 100 cfm, but thought I would ask.