AquaCera CeraUltra 10" Filter W9512500 0.9 Micron absolute pore size for physical filtration, though the nominal pore Micron Rating is 0.5 to 0.8 microns. Removes 100% of cryptosporidium and Giardia, plus more than 99.999% of pathogenic bacteria. The matrix is silver-impregnated to prevent bacterial growth in the wet filter. Removes most volatile organic compounds (VOCs), heavy metals, and other chemicals, including but not limited to lead, arsenic, iron, aluminum, nitrite, pesticides, chlorine, chloramines, COD (chemical oxygen demand), herbicides, solvents, THM (trihalomethanes), and PAH (poly-aromatic hydrocarbons). Leaves beneficial minerals in the water for good flavor and healthful effect. Filtering capacity is 1,000 gallons For the Aquacera and doulton pressure systems only. (Not for gravity use)