A peritoneal dialysis system includes: an automated peritoneal dialysis ("APD") machine (102a) configured to remove ultraf iltrate ("UF") from a patient and record how much UF has been removed; and a logic implementer configured to (i) form a first moving average UF removed trend, (ii) determine a trending range around the first moving average UF removed trend, (iii) determine at least one of an upper and lower UF removed limit from the trending range, (iv) form a second moving average UF removed trend, and (v) alert if the second moving average UF removed trend moves outside of the at least one UF removed limit.