AquaFX TRUE TFC High Silicate Rejection Membrane These top of the line membranes fit any standard residential membrane housing, so you can UPGRADE to an AquaFX RO Membrane Today! This RO Membrane is rated at 100 GPD (or Gallons per Day) - that translates 100 Gallons in 24 hours. Operating pH from 2 to 12 Tolerating a pH of 1 Short Term Maximum Temperature 110 degrees F Amazon Transparency verification now active Here at last are TRUE Thin Film Composite (TFC) reverse osmosis membranes from AquaFX. Extensive testing has demonstrated that DOW's TFC sheets are the best material for membrane applications. Superior membranes = superior performance.