A hemodialysis system, comprising: a blood flow path through which untreated blood is drawn from a patient and passed through a dialyzer; a dialysate flow path through which dialysate flows from a dialysate supply through the dialyzer, the dialysate flow path including a balancing circuit, the dialysate flow path and the blood flow path being in fluidic communication; a pressure device of the balancing circuit being a membrane based dialysate pump configured to pump dialysate in the dialysate flow path; and a blood pump configured to pump blood in the blood flow path, wherein: i. the pressure device is configured to urge dialysate in the dialysate flow path to flow into the blood flow path in the dialyzer, wherein the hemodialysis system is configured so that pressure is controlled within the pressure device in a manner synchronized with the delivery strokes of the blood pump, or matched to pressures generated by the blood pump such that the pressure of the dialysate exiting the dialyzer is lower than the pressure of the blood exiting the dialyzer; or ii. the pressure device is configured to urge dialysate in the dialysate flow path to flow into the blood flow path in the dialyzer, wherein the hemodialysis system is configured so that pressure is controlled within the pressure device in a manner synchronized with the delivery strokes of the blood pump, or matched to pressures generated by the blood pump such that the pressure of the dialysate entering the dialyzer is greater than the pressure of the blood entering the dialyzer; or iii. the hemodialysis system is configured to make dialysate pass through the dialyzer such that dialysate is pushed through the dialyzer from the dialysate flow path into the blood flow path and is pulled back with every dialysate pump stroke of the pressure device. a blood flow path through which untreated blood is drawn from a patient and passed through a dialyzer; a dialysate flow path through which dialysate flows from a dialysate supply through the dialyzer, the dialysate flow path including a balancing circuit, the dialysate flow path and the blood flow path being in fluidic communication; a pressure device of the balancing circuit being a membrane based dialysate pump configured to pump dialysate in the dialysate flow path; and a blood pump configured to pump blood in the blood flow path, wherein: i. the pressure device is configured to urge dialysate in the dialysate flow path to flow into the blood flow path in the dialyzer, wherein the hemodialysis system is configured so that pressure is controlled within the pressure device in a manner synchronized with the delivery strokes of the blood pump, or matched to pressures generated by the blood pump such that the pressure of the dialysate exiting the dialyzer is lower than the pressure of the blood exiting the dialyzer; or ii. the pressure device is configured to urge dialysate in the dialysate flow path to flow into the blood flow path in the dialyzer, wherein the hemodialysis system is configured so that pressure is controlled within the pressure device in a manner synchronized with the delivery strokes of the blood pump, or matched to pressures generated by the blood pump such that the pressure of the dialysate entering the dialyzer is greater than the pressure of the blood entering the dialyzer; or iii. the hemodialysis system is configured to make dialysate pass through the dialyzer such that dialysate is pushed through the dialyzer from the dialysate flow path into the blood flow path and is pulled back with every dialysate pump stroke of the pressure device. i. the pressure device is configured to urge dialysate in the dialysate flow path to flow into the blood flow path in the dialyzer, wherein the hemodialysis system is configured so that pressure is controlled within the pressure device in a manner synchronized with the delivery strokes of the blood pump, or matched to pressures generated by the blood pump such that the pressure of the dialysate exiting the dialyzer is lower than the pressure of the blood exiting the dialyzer; or ii. the pressure device is configured to urge dialysate in the dialysate flow path to flow into the blood flow path in the dialyzer, wherein the hemodialysis system is configured so that pressure is controlled within the pressure device in a manner synchronized with the delivery strokes of the blood pump, or matched to pressures generated by the blood pump such that the pressure of the dialysate entering the dialyzer is greater than the pressure of the blood entering the dialyzer; or iii. the hemodialysis system is configured to make dialysate pass through the dialyzer such that dialysate is pushed through the dialyzer from the dialysate flow path into the blood flow path and is pulled back with every dialysate pump stroke of the pressure device.