A cleaner receives input pulp stock in an inverted conical chamber (26), which acts as a hydrocyclone to direct heavyweight reject flows outwardly, lightweight reject flows into a discharging vortex chamber and accept flows in between to a vortex finder for removal. The cleaner body has an inverted hydrocyclone chamber (34) formed beneath the inverted cone and a ceramic splitter (36) below which skims off the heavyweight reject flow from the accept flow, and diverts it into the inverted hydrocyclone chamber (34). A portion of the diverted heavyweight reject flow is removed through a toroidal heavyweight rejects relief outlet (47), but the larger fraction of the heavyweight reject flow is recirculated within the inverted hydrocyclone chamber. Because the chamber narrows as it extends upwardly, the flow increases in speed and angular velocity to such an extent that the flow within the inverted hydrocyclone chamber matches the flow passing by the chamber, thereby preventing turbulent mixing.