Trying this-Magic Eraser uses... did you know you can cut a piece off and float it in your toilet overnight and voila! no more toilet ring! -clean window screens (even when they are still in the window) The website has a list of about 100 uses!
How to Use Vinegar and Baking Soda to Clean a Toilet Naturally
Get rid of the hard water ring around your toilet bowl! Use 2 cups of vinegar and sprinkle 2 tablespoons of baking soda and watch the stains start to sizzle away...use an SOS pad to scrub away any stubborn marks/stains.