A filter (10) includes a liquid holding vessel (12) with an inlet (14) and an outlet (16). A removable filter cartridge (24) is positionable within the vessel. The cartridge includes a plurality of filter element assemblies (82) each of which includes a plurality of filter elements (86). Filter elements are selectively back flushed through a back flush assembly (26) which includes a positionable back flush conduit arm (28) that rotates in response to a back flush arm shaft (36) that extends in a shaft support (46) of the filter cartridge.