About This PUMICE STONES CAN TAKE HOURS - Guardian works while you do something else. Spray on scaled surfaces & leave it. Removes scale progressively (see photos). Apply weekly until scale is gone. Heavier scale will take more applications. This is an "above the waterline" treatment. SCOURING NEVER REMOVES 100% OF DEPOSITS. Stones not going to work on textured or sculpted tiles. GUARDIAN FINDS CALCIUM YOU CAN’T SEE. Also breaks down scum line. SCRUBBING TILES WEARS OUT YOUR ARMS – save your arms/shoulders & let Guardian work at the chemical bond level to remove calcium. NON-CORROSIVE – Contains no harsh acid that can damage surfaces. NON-ABRASIVE – pumice stones can scratch tiles and even remove numbers. Guardian won’t do that. TARGETS CALCIUM that mechanical SCRUBBING WON'T REMOVE. SAVE $100’S compared to the cost of 3rd party removal SAFER TO USE – will not affect pool chemistry, contains no phosphates or brighteners. Designed to Federal BioPreferred Standards. NOT RECOMMENDED for use on porous surfaces like natural stone and cement tiles. MORE QUANTITIES & OPTIONS - search GUARDIAN POOL & TILE. Made in USA. Overview Brand : Generic Item Weight : 38 Pounds Item Volume : 4 Gallons Package Information : Bottle Item Form : Spray