AQUAMIX PHOSPHORIC ACID CLEANER is a concentrated acid and cleaner designed to penetrate below the surface to remove light grout smears, mineral deposits, rust stains and efflorescence. Also effective for removal of most hard water stains, lime deposits and soap scum. Uses: Recommended for use on masonry surfaces and acid-resistant tile and stone. Coverage: Depending on dilution, approximately 400 to 1,200 sq. ft. per gallon.