【Function】The osmosis membrane to lower the TDS level of water. It is a ULP1812-75G round composite film. It mainly eliminates heavy metals (mainly calcium and magnesium, lead, chromium and nitrates). You put the new membrane in an empty housing, turn off the old housing and the membrane, and run the system for about 1/2 hour. The system is ready at this time, you test the end of TDS to confirm. 【RO cartridge】This reverse osmosis filter uses composite material. The membrane produces 75 gallons of water (1 US gallon = 3,785 liters) for 1 day (24 hours) at a temperature of 25°C and a water pressure of 5.5 kg. If you want to get better results in reducing the TDS level of the water, we recommend that you replace this membrane regularly. 【75 GPD Universal Compatible】Reverse Osmosis Membrane is used in the desalination treatment of surface water, ground water and running water with a salt content of about 2000 ppm or less. Start recording your TDS and The membrane is pressure treated every