Aries Filter Works 3300 series Phosphate Cartridge contains food grade, slow melt polyphosphate that dissolves in water to inhibit scale and rust build up. This filter is used primarily where scale, corrosion and increased amounts of iron are present in the water source. Phosphate cartridges are also available in combination with coconut shell GAC. The additional combination improves taste and odor and removes chlorine. About Phosphate As a mineral, phosphate is not seen as harmful and is safe to ingest at reasonable levels. Phosphates are derivatives of phosphoric acid, which contain phosphorous and oxygen and exist in inorganic and organic forms. They are widely used in water treatment and industrial formulations because of their superior ability to soften water, control scale and corrosion, and sequester iron, calcium and manganese. Additional Details ------------------------------ Product description: Aries Filter Works 3300 series Phosphate Cartridge contains food grade, slow melt polyphosphate that dissolves in water to inhibit scale and rust build up. This filter is used primarily where scale, corrosion and increased amounts of iron are present in the water source. Phosphate cartridges are also available in combination with coconut shell GAC. The additional combination improves taste and odor and removes chlorine. About Phosphate As a mineral, phosphate is not seen as harmful and is safe to ingest at reasonable levels. Phosphates are derivatives of phosphoric acid, which contain phosphorous and oxygen and exist in inorganic and organic forms. They are widely used in water treatment and industrial formulations because of their superior ability to soften water, control scale and corrosion, and sequester iron, calcium and manganese.