The present invention relates to an apparatus for carrying out a tidal peritoneal dialysis treatment of a patient, wherein the dialysis treatment comprises a sequence of cycles which each have a filling period, a dwell period and a drain period, wherein the apparatus has at least one cycler which is suitable for filling the abdominal cavity of the patient with a specific inflow volume of fresh dialysis solution up to a reaching of a specific patient volume in the filling period and for emptying consumed dialysis solution from the abdominal cavity of the patient up to a reaching of a specific tidal outflow target in the drain period, wherein the apparatus furthermore has at least one processor which controls the cycler in at least one operating mode such that the drain period is ended before reaching the tidal outflow target so that a permitted residual volume remains in the abdominal cavity and then a switch is made to a filling period and in that the filling period is carried out such that the filling volume of the patient lies at a permitted patient volume above the specific patient volume on the completion of the filling period.