The Hydro Life Hydroponics KDF 85 Replacement Cartridge has Catalytic Carbon filtration to provide you with safer, cleaner water from any potable source. Catalytic carbon along with KDF 85 can reduce up to 98 percent of chloramines and heavy metals from potable water. KDF 85 bonds and traps heavy metals and can help prevent bacteria growth when the filter is not in use. Replacement Cartridge has a 8,000 gallon capacity with up to 2.5 GPM flow rate. When first attaching the filter to your water source, allow the water to run free for a few minutes to flush the initial loose carbon fines out of the filter. When the water runs clear, the filter is ready for use.