Abstract: A bypass feeder of the type comprising a tank having a closeable rounded top opening, an inlet and outlet opening positioned on the side of the tank, includes a rectangular frame filter bag holder dimensioned to fit inside the tank, the frame having its bottom portion fitted with a plug having a tapered round opening, an L-shaped inlet pipe adapted to be received into the tapered opening of the plug, a filter bag dimensioned to fit over the filter bag holder and having a drawstring adjustable bottom opening for fitting the opening tightly against the plug. The improvement of the invention resides in the filter bag also having an open top and a sealing ring adapted to engage the open inside top of the filter bag and force seal it against the inside of the closeable rounded top opening.