Just like a capful per gallon. Not alot.How much bleach? I'm also going to be looking into getting some new water pan's for mine because I want to get away from using these galvanized metal one's. They are starting to look bad in the bottoms. They stand in those too. Black one's sound like they might work better.
I go to the Dollar General/Dollar Tree type stores and get the cheap cat litter pans and dish pans. Walmart has similar dishpans, too. If they get too nasty or whatever I don't have to care because they're cheap. So I just get a stack and use a couple at a time. I always end up using some for other things too.. (just like in the pic.. haha!!)