Phosfree 2LMOST EFFECTIVE WAY TO REMOVE PHOSPHATES Reducing phosphate levels in pools is easy with Natural Chemistrys patented Phosfree technology. Phosfree is formulated from lanthanum (rare earth) compounds. When added to the skimmer, a thin coating of Phosfree forms on the filter media. As pool water flows through the filter, phosphates are reduced to a very low level. Most effective way to remove phosphates prior to using a weekly maintenance product Works