A couple of weeks ago I finally adopted two cats (both 2 years old, from different shelters). One of the two does not cover his poop, probably because he never learned to, and it's too late to teach him now. The other cat actually does double duty if he finds uncovered poop in the litter box, covering (so to speak) for his roommate. Anyway, the stuff stinks really badly, and the exhaust fan in my inside bathroom does not do an adequate job of clearing up the air.

I have one of those covered litter boxes (the Van Ness CP7), and it already has vents on the top (with zeolite filters that don't do anything), so I'm thinking of attaching some sort of fan that would pull the air and force it through an activated charcoal filter. Does such a thing already exist? I haven't been able to find anything on Amazon. I've looked at lots of small air purifiers, and none appear to be suitable for fitting on top of the box.

Suggestions? Pointers?

I also assume the carts won't like it if there is a whirring fan and air movement while they do their business, so a PIR sensor and a relay connected to an Arduino would take care of that. Plus, it would get me statistics for how much and how long they use the box for while I'm away :)