Finerfilters 4 Stage Compact Aquarium Reverse Osmosis Replacement Water Filters and 100 GPD Membrane \nRemoves very high levels of most impurities from the water, ideal for filtering tap water for your Aquarium. \nIncludes: \n- 1 x Sediment Pre-Filter \n- 1 x Post Carbon Filter \n- 1 x Bag of DI Resin \n- 1 x Reverse Osmosis Membrane 100 GPD \nPlease note: this is for RO replacement filters and membrane only. Fittings are not included. PTFE tape will be required when installing fittings. \nReverse Osmosis is a technology that is used to remove the large majority (98%+) of contaminants from water. The reverse osmosis system works by pushing the water under pressure through a number of increasingly smaller filters and finally through a semi-permeable membrane essentially trapping all contaminants.\nFinerfilters 4 Stage Compact Aquarium Reverse Osmosis Replacement Water Filters and 100 GPD Membrane \nRemoves very high levels of most impurities from the water, ideal for filtering tap wate