Quote Originally Posted by MarkS View Post
Well then he just doesn't clean often enough or have very good ventilation. All rodent colonies will have a build up of ammonia no matter how often or well you clean. Proper ventilation is a must. If it's unpleasant for you, it's not doing the mice any good either.

If you scrap the pans well and don't leave any crusty stuff behind, the smell is very minimal. It's worked well for me for many years.
Your correct, he didn't have very good ventilation.