I use the Mr. Clean Magic Erasers found in your local supermarket in the cleaning isle to clean the Hard water deposits off of my showerstalls, and sinks, etc. These things are AMAZING. I've tried CLR and Limeaway, even scraped everything with a little straight edged razor. Nothing works as good as the Mr. Clean product. I'm not sure if there are any chemicals you would need to be concerned about leaving residue, so read the box before you try it.