Get rid of the scum hanging around your pool. Featuring Earth Smart® Acid technology, this tile cleaner and renovator is safe and economical to use. United 431 removes scum, algae, body oils and suntan lotions from pool tile and walls. It clings to vertical surfaces and contains no ingredients that would harm bathers when used as directed. United 431 is a strong performer in the pool, removing calcium carbonate scale two to three times faster than other phosphoric acid products.