I have a rental house which just became vacant. I notice in the toilet
tanks, there is a mold / mildew problem. I'm not sure why since the
house a/c works fine. Anyway, what is the best way to clean this
inside the tank? I'm thinking of spraying bleach but I'm a little
afraid if that will hurt the plastic guts or rubber seals inside the
tank. Suggestions? Also any idea how to prevent this from happening
again over time?