Use the wrong cleaner and you could etch the surface then you will have to re-polish and this will be expensive. I use the product and never had a problem. Just test on a small area first and follow instructions.
Aqua Mix Phosphoric Acid Substitute is a premixed acidic treatment designed to remove grout haze, mineral deposits, rust stains, mortar smears, and efflorescence. Effective for the removal of most hard water stains, lime deposits, and soap scum. Also removes cement grout and mortar residue from tile, concrete, and masonry. Etches concrete. No VOCs, No phosphates.
Aqua Mix No VOC (Volatile Organic Compound) formulas help provide better indoor and outdoor air quality compared to similar traditional products.
Uses
Acid resistant natural stone (such as granite and slate), ceramic, porcelain, quarry, saltillo, terra cotta, and other acid resistant tile and stone.