I recently saw a posting on Facebook about removing hard water stains on a tub by using a toothbrush and some toothpaste. Furthermore, it suggested other recipes, such as a mixture of borax and lemon juice or vinegar and water. It even mentioned turpentine!! I have never tried any of these to verify that they work, but I have had success with using CLR. I’ve also tried using liquid Vim with success. I would never try these on a refinished or reglazed surface for several reasons. A refinished tub dries under room temperature and not under extreme heat, the new enamel or glaze is porous. If strong chemicals or dyes are used on the tub, it leaches down to the primer coat level and oxidizes it. This in turn will cause the tub to turn yellow, the paint will become brittle and will eventually crack, chip or peel. A refinished surface needs to be treated a little different than one that isn’t refinished. Because it’s cured under room temperature, the bonds between the coats are strong but not permanent, therefore, using scrubbing brushes, scotch-brite pads and other abrasives will actually damage the glaze. Dr Tubs Reglazing suggests that you clean your refinished surface regularly (at least once a week) with a soft cotton face cloth, and a non-abrasive cleanser. Some cleansers you can use are: Mr Clean, Dawn dish soap, Palmolive dish or kitchen liquid detergents, Fantastic or any liquid bathroom or kitchen detergent that doesn’t contain bleach and harsh dyes. There are a lot of natural cleaning products that can be used. The key to a clean tub is regular cleaning. This prevents soap scum and human skin/hair oils from adhering to the surface. There is no need to scrub at all if it’s cleaned often.