A renal failure therapy machine includes a blood cleaning filter, a sorbent device configured to regenerate used therapy fluid from the blood cleaning filter, a therapy fluid pump configured to pump regenerated therapy fluid from the sorbent device back to the blood cleaning filter, and a flow restrictor in fluid communication with the blood cleaning filter, the therapy fluid pump and the sorbent device, the flow restrictor configured to cause regenerated therapy fluid pumped by the therapy fluid pump from the sorbent device to the blood cleaning filter to be pressurized so that a first amount of the regenerated therapy fluid performs convective clearance and a second amount of the regenerated therapy fluid performs diffusive clearance.