Sani Marc Summer Smiles 30-07000-04 4L Klean Surface All-Purpose Cleaner is an aqueous solution of 29% hydrochloric acid. It cleans concrete efficiently to improve the adherence of paint work. Effectively eliminates efflorescence salts and calcareous deposits, and can also be used to clean bricks, stones, ceramics and concrete pools. KLEAN SURFACE can also be used to lower pH and total alkalinity in pool water.