I work at a pool in a mining town, and over the years the dust in the air has stained the tiles. Does anyone know what gets its out. None of the branded cleaners from the hardware shops work, nor does hyrochloric acid, bi-card soda, soda ash or caustic soda.
If anyone can give me any other chemicals or anything for that matter that will get the stain out of the tiles please help.

Cheers,