Applied Biochemist 400500 Removit Stain Remover 2 lb Stain Remover has Biodegradable granular formula which quickly removes existing stains caused by iron, copper, cobalt and manganese without draining Can be used in the entire pool or made into a paste to remove the toughest metallic stains No testing is required Compatible with all sanitizing systems and does not affect pH or sanitizer levels Also compatible with chlorine, bromine, biguanide and salt water sanitizing systems