A method and device for performing extracorporeal blood treatment utilizes a first concentrate connection configured to feed a first concentrate into the device as a basis for generating a dialysate, and a second concentrate connection configured to feed a second concentrate into the device as a basis for generating a dialysate. In operation, a first concentrate is fed into the device through the first concentrate connection. The method and device then switch over from feeding the first concentrate into the device through the first concentrate connection to feeding the second concentrate into the device through the second concentrate connection. The switchover step can be performed at a predetermined time during an ongoing blood treatment or after a predetermined period of time.
