There is a product called "Lime Away" - bright green bottle. I use it in the shower, the toilet bowls, everywhere because we have so much lime in our water. Also been using Borax (in laundry aisle) and adding a bit to the dishwasher. Also going to try Borax in the tub and in the base of our shower. We squeegie our shower doors and inside the shower also. I got clear glass instead of the frosted patterned kind just so we would do it every time. Just takes a minute and really helps. There is a product that you buy at automotive supply stores - clear glass or something. It left a film, but the water didn't make stains on the glass.