I can certainly vouch that the DIY Air Purifier works!

http://ball-pythons.net/forums/showt...light=purifier

I am running 6 bins with either 1.3 or 1.4 plus babies. My rats are in my living room... Yes, living room (1br apt) when the weather is too cold. They are in for a week or two at a time.

I have the DIY fan, use pine pellets in combination with regular bedding, I try not to crowd the bins and I change them twice a week.

I know this isn't what you asked advice for, but it may help in the meantime of you putting in the exhaust fan.