A control or regulating apparatus configured, to execute or initiate a process for controlling the blood treatment apparatus, in cooperation with a blood treatment apparatus, which comprises a blood pump for conveying blood within an extracorporeal blood tubing set as well as a dialysis liquid pump for conveying dialysis liquid within a dialysis liquid circuit, which comprises a dialysis liquid feed line, which can be interrupted by means of a dialysis liquid feed line clamp of the blood treatment apparatus, and a dialysate drain line, which can be interrupted by means of a dialysate drain line clamp of the blood treatment apparatus, wherein the blood tubing set comprises an arterial portion comprising an arterial patient tubing clamp or being connected thereto; wherein the blood tubing set comprises a venous portion comprising a venous patient tubing clamp or being connected thereto; wherein the blood tubing set comprises or is connected to a blood filter having a membrane which separates a blood chamber from a dialysis fluid chamber, and which is arranged between the arterial portion and the venous portion, wherein the process comprises the automatically performed steps of: a) closing the arterial patient tubing clamp and the venous patient tubing clamp; b) conveying dialysis liquid by means of the dialysis liquid pump; c) opening the venous patient tubing clamp; d) closing the dialysate drain line; e) preventing or ending the dialysis liquid flow, as soon as a predefined first volume, after deduction of a second volume, has passed over the membrane, the second volume preferably corresponding to the volume of the arterial portion of the extracorporeal blood circuit up to the inlet of the blood filter; f) closing the venous patient tubing clamp; g) conveying dialysis liquid by means of the dialysis liquid pump; h) opening the arterial patient tubing clamp while the dialysate drain line remains closed; j) closing the arterial patient tubing clamp; k) stopping the dialysis liquid pump as soon as the second predetermined volume has been conveyed or air or clot has been detected by a sensor; wherein the process further comprises the following steps or alternatively steps 1) to q) or steps r) to s): 1) starting up the dialysis liquid pump or a dialysis liquid pump located downstream of the blood filter or an ultrafiltration pump located downstream of the blood filter; m) closing or keeping closed the dialysis liquid feed line; n) opening the dialysate drain line clamp; p) opening a ventilation valve; q) sucking dialysis liquid out of the blood tubing set via the membrane by means of the dialysis liquid pump; r) opening the dialysate drain line; s) introducing gas into a connecting line to the venous pressure sensor, which displaces the dialysate through the membrane to the dialysate outlet side; u) stopping the dialysis liquid pump; and w) issuing an alarm or an indication to inform dialysis personnel about the end of the process. a) closing the arterial patient tubing clamp and the venous patient tubing clamp; b) conveying dialysis liquid by means of the dialysis liquid pump; c) opening the venous patient tubing clamp; d) closing the dialysate drain line; e) preventing or ending the dialysis liquid flow, as soon as a predefined first volume, after deduction of a second volume, has passed over the membrane, the second volume preferably corresponding to the volume of the arterial portion of the extracorporeal blood circuit up to the inlet of the blood filter; f) closing the venous patient tubing clamp; g) conveying dialysis liquid by means of the dialysis liquid pump; h) opening the arterial patient tubing clamp while the dialysate drain line remains closed; j) closing the arterial patient tubing clamp; k) stopping the dialysis liquid pump as soon as the second predetermined volume has been conveyed or air or clot has been detected by a sensor; 1) starting up the dialysis liquid pump or a dialysis liquid pump located downstream of the blood filter or an ultrafiltration pump located downstream of the blood filter; m) closing or keeping closed the dialysis liquid feed line; n) opening the dialysate drain line clamp; p) opening a ventilation valve; q) sucking dialysis liquid out of the blood tubing set via the membrane by means of the dialysis liquid pump; r) opening the dialysate drain line; s) introducing gas into a connecting line to the venous pressure sensor, which displaces the dialysate through the membrane to the dialysate outlet side; u) stopping the dialysis liquid pump; and w) issuing an alarm or an indication to inform dialysis personnel about the end of the process.