RPI-5000A is specially designed to inhibit SiO2 scale formation in RO-systems with polyamide, cellulose acetate and polyether membranes with negative or neutral charged surface. RPI-5000A is a stabilized solution blend of polymers and copolymers suitable for use within broad pH ranges. It is the most effective inhibitor against colloidal and dissolved SiO2 deposit on the membrane surface. The allowable silica content in the RO-concentrate stream can be as high as 260 mg/l under the normal plant operating conditions. The product does not contain any phosphonates and phosphates.