I had thirty years of mineral rust in my Tucson toilet, where the water is hard hard hard. Every product I tried failed to remove the rust stain in the bottom of the bowl. Here's what I did: I poured a gallon of water into the bowl so it would flush and not refill. I then poured a half bottle of Descale-it Toilet Bowl Cleaner into the bottom of the bowl where it adhered to the nasty rust. I left it overnight. In the morning, I could see the first improvement in thirty years! I scrubbed with a soft pumice stone for a few minutes, and the rest of the rust disappeared with the first flush. My toilet looks like new! Thank you, Descale-it manufacturers! I shall sing your praises all over the internet!