Phosphate crystals are used to help prevent lime and scale build up on pipes and glass. It is also effective for treating corrosion and iron problems. Phosphate used in this cartridge was tested and listed under NSF Standard 61. This type of treatment is recommended for use with ice machines, coffee and vending machines, food service equipment, water heaters, air conditioning equipment and many other types of water processing equipment. Additional Details ------------------------------ Product description: Phosphate crystals are used to help prevent lime and scale build up on pipes and glass. It is also effective for treating corrosion and iron problems. Phosphate used in this cartridge was tested and listed under NSF Standard 61. This type of treatment is recommended for use with ice machines, coffee and vending machines, food service equipment, water heaters, air conditioning equipment and many other types of water processing equipment.