Abstract: A small tubular cartridge for processing of ultra low volumes of gravity flow spent photographic fixer solution to recover residual silver therefrom. The tube cartridge comprises a hollow transparent or light transmitting flexible plastic tube of synthetic resinous material such as vinyl. The transparent tube is closed by an impervious bottom end cap which is bonded or otherwise integrally secured to the lower end of the transparent tube, with a top end cap being similarly secured to the top end of the tube and providing a central axial solution outlet opening and an eccentric solution inlet opening, each opening having a downwardly directed collar. A central solution exit tube is disposed substantially coextensive and coaxially with the transparent tube and is integrally secured as by bonding at its upper end to the central axial effluent solution opening.