a filter apparatus includes a endless filter belt loop disposed in an interior space within a tank which receives liquid to be filtered . the filter belt has a series of closely spaced parallel guide - flight bars attached which are successively engaged by an extendible element on a pivot plate which is periodically oscillated to under the filter belt . the bars are received in guide spaces to hold the filter belt in position over a filter support having openings allowing filtering flow thererthrough . collapsible sealed hoses partially filled with liquid are used as edge seals extending along the guide spaces over side edges of the filter belt and are expanded by engagement of an upper end of each of the hoses with a squeeze member on the pivot plate . the squeeze members are moved off the hoses when the pivot plate is oscillated to advance the filter belt during indexing to release the sealing pressure and allow filter belt indexing movement . the pivot plate oscillation also operates a beater bar to guide the belt to dislodge solids from the belt . in a vacuum version , the filter belt support is provided by molded plastic support pieces assembled over a solid curving support plate in the tank .