Twin Gravel (Moss) Filter Systems Used for filtering moss and algae format ions in the water. Used for waters acquired from lakes, channels and rivers. The most important fact is Basalt and quartz sand in Sand (Moss) filter. For Sand (Gravel) Filters; For 18” Sand (Moss) Filters: 3 bags (2 – 4) basalt sand. For 24” Sand (Moss) Filters: 5 bags (2 – 4) basalt sand . For 36” Sand (Moss) Filters: 10 bags (2 – 4) basalt sand. Technical Details Twin Gravel (Moss) Filter Systems Product CodeInput-OutputBody DiameterMushroom PcsCapacity GBMI-PDIS-404"36"120 Pcs70-90 m³/h