GrowoniX Green Coconut Replacement Carbon FiltersEco Friendly Green Block Coconut Carbon Filter: NFS61 Listed Green carbon. High flow with a low carbon footprint. Reduces taste, odor, chlorine and certain VOC's from water. Manufactured with High Purity Coconut Shell Activated Carbon. High Chlorine reduction and great dirt holding capacity. NSF Standard 42. 8,000 total gallons of chlorine removal, or 2,500 gallons of purified (RO) water at a 2: 1 ratio.