<p>A cylindrical housing is adapted to receive and discharge fluid in a subterranean well. In a preferred form, a plate is positioned in the cylinder separating it into first and second chambers. Filter adapter receiving means are disposed across the plate, with a filter adapter securable therein, the adapter having a passageway extending to the chambers. The adapter has a cylindrical housing having an enlarged cartridge positioning portion. A grooveway is defined on the adapter extending exteriorly therearound for securing one end of a cartridge filter. A cartridge filter is positionable on the adapter and provides a seal having an interiorly facing circumferentially extending lip for contact with the exterior of the cylindrical housing when the filter is located on the adapter, for sealingly securing the filter to the adapter.</p>
