Continuum Aquatics Membranes 100gpd Hi Flow High quality reverse osmosis membranes made in U.S.A. This HiSil High Silicate removal membrane is the only membrane in the world that is made from specially manufactured high technology material that rejects, by design, silica and silicates, while rejecting the largest amount of phosphates, nitrates and other undesirable ions from tap water. Other membranes are artificially treated with chlorine to “seal” the membrane surface. This causes a temporary increase in silicate rejection but shortens the membrane life substantially by damaging the material. All our membranes are made in the United States.