Bought these to remove water stains in toilet. Worked perfectly. Used about one per toliet. They do dissolve

This product will clean grout very effectively and does not take a long time. It beats the chemical cleaners by a long shot without leaving the chemical scents.

best product to use for toilet with hard water stain

Excellent for removing hard water stain

I bought this pumie to remove the build up on our pool tiles. The build up was not extensive. It did remove the build but one block only cleaned 4 small pool tiles. We went through a full box and it only cleaned 1/4 of the tiles, if that many. If you have a small project these would work, but not for any medium to large projecta.