A system for extracorporeal blood treatment is disclosed that includes a haemofiltration device, a pump for pumping blood through the haemofiltration device, citrate means upstream to add citrate, calcium means downstream to add calcium solution, and a control configured to activate or inactivate the citrate addition means and/or the calcium addition means, wherein the control activates the citrate addition means at the beginning of blood treatment and for a first time period filters the blood with activated citrate addition means and continues to operate the citrate addition means until the end of blood treatment activates the calcium addition means after the first time period has elapsed when the total extracorporeal blood volume in the system has been filtered and citrate treated, continues to operate the calcium addition means in an active state during blood treatment to stably maintain a user-determined calcium addition rate, and continues to operate the calcium addition means in an active state after the end of blood treatment, until a second time period has elapsed after the end of treatment. A method of controlling such a system to ensure adequate calcium replenishment after citrate anticoagulation is also disclosed.
