Suspended solids, residue and turbidity in water are eliminated by multi layered sand filters. They are used in deep water, lake water, in the pre-treatment of reverse osmosis and in waters where turbidity is < 6 NTU. With multi layered sand filters, all particles up to 20 micron are eliminated with high efficiency. Fleck control valve systems: Fleck control valve sand filters FRP (fiberglass reinforced polypropylene) consist of a filter tank, a distributor system, media material and an automatic control valve. These systems perform time dependent back washing.  

Surface Piped Systems: Surface piped systems FRP or epoxide covered carbon steel tanks are made up of a distributor system, media material, a butterfly valve with actuator, manometer and a PLC based control panel. Surface piped systems perform time dependent and/or pressure difference controlled back washing. The distributor system in the filter tank distributes and collects the water in the tank uniformly during service and washing. The filter contains anthracite, sand and three grades of gravel, respectively. When the water is drained through this multi layered media, all particles that cause turbidity are held back. In addition, the filtration of steel and manganese compounds oxidized by chloride and turned to particles, is carried out by multi layered sand filters.