Stain & Scale cleanse is a phosphate-free sequestering agent designed to ionically bind to dissolve calcium and metal ions, preventing the formation of stains and scale. Metal deposits often go unnoticed and scale deposits can damage water heaters and roughen surfaces. This high quality product is now even more stable in high chlorine levels and performs better than competitive products in high pH. Stain & Scale Cleanse is ideal for opening a pool when a large amount of water and balancing products are added.