Fine Sand mild steel water flow Coarse Sand Key Features filter media large volumes Layered Media water quality high flow rate multiple layers finer particles stainless steel water treatment different sizes initial removal suspended solids other impurities larger particles robust materials filtration media backwashing system water distribution long-term operation smaller applications residential settings multi-grade layering High Filtration Rate Backwashing Capability varying particle sizes fiber-reinforced plastic Multi-Grade Sand Filters A Multi-Grade Sand Filter advanced filtration system Effective Particle Removal municipal water supply systems