Punch a hole in the top of a bottle of vinegar and sit the bottle in your toilet tank. In doing this you will save water, as the tank wont fill as much, the vinegar will clean your toilet AND tank on each flush, it leaves the bathroom smelling fresh and it doesn't harm any component of your toilet OR the environment when flushed.
Sorry about the picture! Keep this in mind if you start seeing lots of spiders around your place. Natural spider killer or preventer... take one cup of vingar, one cup of pepper, a teaspoon of oil and liquid soap. Put it into a spray bottle and spray along the outside of your outside door and along windows; refresh after it rains.