I keep around 20 breeder Rats, 20 mice, 20 asf, and all there young. I am cleaning them weekly, I keep them In The basement with my herp collection. I have a false ceiling and I'm thinking of installing a small fan to suck out the smell? I can smell it upstairs sometimes and it stinks! I thought of putting a shed outside with heating and cooling but the cost and I have a sink in the basement ... so the real question is who knows where I can get a low cfm fan to suck out the smell? And do i have to drill a hole on the exterior of my house? The room is 15x 25' thanks!