An infusion system comprising: a first delivery unit that delivers an infusion ultrafiltrate to a hemofilter a first measurement device that determines an amount of infusion ultrafiltrate in the infusion system a receiver unit that receives a patients removed ultrafiltrate from the hemofilter a second measurement device that determines an amount of removed ultrafiltrate in the infusion system and a control system communicating with the delivery and receiver units and the first and second measurement units to determine optimum flow rates to and from the hemofilter, based upon the determined amounts of infusion ultrafiltrate and removed ultrafiltrate in the infusion system, and a predetermined desired pressure differential between the infusion and removed ultrafiltrates, and for controlling the delivery and 15 receiver units accordingly.
