Reverse osmosis scale inhibitor (acid) is a high-efficiency reverse osmosis scale inhibitor, which is especially suitable for scaling caused by metal oxide, silicon, carbonate, sulfate and iron oxide precipitation. It has high scale inhibition efficiency and does not agglomerate with residual coagulant or aluminum rich and iron rich silicon compounds to form insoluble polymers. Applicable to all water sources, especially well water. The scale deposition of CaCO3, CaSO4, SrSO4, BaSO4, CaF2 and SiO2 can be controlled. Under the condition of no acid, the maximum allowable LSI value is 2.8, which can be used to produce drinking water (in accordance with ANSl / NS F60 certification standard). It is applicable to all major reverse osmosis membranes and various membrane products produced by major manufacturers in the world, such as Dow. Filmtec, Ge, Hydranautics, Toray and Shihan.