A monitoring device is operated to detect a disruption of a fluid connection between two fluid containing systems. A disruption detector in the monitoring device operates on a measurement signal (Pi) to detect an apparent disruption of the fluid connection and generate a corresponding alarm indication. The monitoring device is configured to optimize the configuration of the disruption detector to limit the number of false alarms, by operating a false alarm analyzer to produce a count (FA#) of false alarm indications generated per unit time by the disruption detector for one or more configurations (Δ；L) of the disruption detector, and by operating an updater to update the configuration (Δ；L) of the disruption detector based on the count (FA#). The monitoring device may be connected to or part of an apparatus for blood treatment and operable to detect a disconnection of an extracorporeal blood circuit from a vascular system of a patient, e.g. a venous-side disconnection.
