Hydro Logic MicRO 75 Membrane FilterReduces 98%+ of PPM of total dissolved solids (TDS) 75 GPD Replace when product water flow rate decreases and or PPM increases RO output depends on the source water temperature. At 77, the system should produce 100% of the rated output. As the temperature drops or increases, so does the output. If you would like to know the TCF specifically for your wanted output, check out our TCF chart. TCF Chart (Temperature Correction Factor)