The Tile Plus Stuff™ has been specially developed to keep pool tile, grout, vinyl liners, and fiberglass looking their stain-free best. The Tile Plus Stuff™ has gel-like properties that adhere to the surface of tile, grout, vinyl liners, and fiberglass for maximum cleaning of scale, metal stains (including rust), oils, and cosmetics. This product will not etch tile or grout when used as directed and is compatible with all pool sanitizer systems.