Green Envy muriatic acid replacement is an inhibited, non-fuming hydrogen chloride solution that safely etches concrete and cleans brick and masonry. It produces 90% less fumes and is safer to use than muriatic acid. Use Green Envy muriatic acid replacement to remove rust, mineral spirits and deposits from tools and other steel items or to balance pH levels in your swimming pool. Apply it with a plastic bristle scrub brush and rinse thoroughly with water.