We do a combination of things. We have an air purifier with a hepa filter right next to it and we mix Feline Pine with regular clay litter. The Feline Pine really helps out with the amonia smell. Cammie Cat can clear a room after she goes. And since she doesn't cover it up..... We clean both cat boxes (1 upstairs, 1 downstairs) every day so that also keeps the smell down.