A pump system including a pump, an inflow cassette and an outflow cassette. The inflow cassette has a damping flexible membrane covering a damping region configured to dampen pressure pulsations in washing fluid passing through the damping region. The pump has a plurality of individually actionable pressing members that can each be individually actuated to pinch one of a plurality of suction tubes of the outflow cassette to at least partially prevent fluid flow through the one of the plurality of the suction tubes.
