When I was breeding mice I would use it in their large water bottles, and I noticed it would get really gunky after a couple of days. I don't really have an odor with the rats other than the ammonia smell, but it would probably work out better because I refill their water a lot more often.

I have been using Stall Dry with the rats and have noticed that it REALLY cuts down on the ammonia smell. The Stall Dry is a little pricey over here and I can buy a similar cat litter product for much cheaper, so I'll probably give that a try after I run out of the SD.