Filter bed filter refers to the traditional medium filter, mainly sand filter. Because of the high requirements of backwash of filtration system, the combination of air and water backwash and surface wash has strong cleaning ability and is very suitable for deep treatment process. In the selection of pool type should avoid the selection of siphon filter with poor backwashing ability of the pool type, and should give priority to the selection of type filter, mobile cover filter, active sand filter and other pool type.