A dialysis system is described. The system comprises at least one dialysis fluid pump for pumping a dialysis fluid to and from a patient over a treatment and a logic implementer. The logic implementer is configured to control the dialysis fluid pumped by the at least one dialysis fluid pump to and from the patient over the treatment and to store a trend of ultrafiltration ("UF") data points for the patient. It is also configured to: (i) use at least one of the UF data points to predict the patients intra-peritoneal volume ("IPV") at the end of at least one dwell and/or (ii) use one of the UF data points in a tidal treatment to predict a residual volume of effluent fluid left in the patients peritoneum after at least one patient drain.
