A method for determining the duration of the service and brine/slow rinse steps in a process cycle for a water conditioner having a bed of ion-exchange material, comprising: positioning a sensor probe and a reference probe in the bed of ion-exchange material vertically displaced from each other, with the sensor probe upstream of the reference probe; monitoring a voltage from each of the sensor probe and the reference probe over a plurality of time intervals; calculating the percent change in the impedance ratio for the current time interval over the minimum impedance ratio of the service step; detecting an increase in the change in impedance ratio if the percent change in the impedance ratio exceeds a first predetermined increase for a first minimum time period; terminating the service step based on said detecting step; initiating a brine/slow rinse step; monitoring a voltage from each of the sensor probe and the reference probe over a plurality of time intervals; calculating the percent rate of change in the impedance ratio for the current time interval from the impedance ratio of a previous time interval; detecting a first peak in the rate of change in impedance ratio if the percent rate of change in the impedance ratio exceeds a predetermined first rate change for a predetermined second time; monitoring a voltage from each of the sensor probe and the reference probe over a plurality of time intervals; calculating the percent rate of change in the impedance ratio for the current time interval from the impedance ratio of a previous time interval; detecting a second peak in the rate of change in impedance ratio if the percent rate of change in the impedance ratio exceeds a predetermined second rate change for at least a predetermined third time; and terminating the brine/slow rinse step based on said third detecting step. positioning a sensor probe and a reference probe in the bed of ion-exchange material vertically displaced from each other, with the sensor probe upstream of the reference probe; monitoring a voltage from each of the sensor probe and the reference probe over a plurality of time intervals; calculating the percent change in the impedance ratio for the current time interval over the minimum impedance ratio of the service step; detecting an increase in the change in impedance ratio if the percent change in the impedance ratio exceeds a first predetermined increase for a first minimum time period; terminating the service step based on said detecting step; initiating a brine/slow rinse step; monitoring a voltage from each of the sensor probe and the reference probe over a plurality of time intervals; calculating the percent rate of change in the impedance ratio for the current time interval from the impedance ratio of a previous time interval; detecting a first peak in the rate of change in impedance ratio if the percent rate of change in the impedance ratio exceeds a predetermined first rate change for a predetermined second time; monitoring a voltage from each of the sensor probe and the reference probe over a plurality of time intervals; calculating the percent rate of change in the impedance ratio for the current time interval from the impedance ratio of a previous time interval; detecting a second peak in the rate of change in impedance ratio if the percent rate of change in the impedance ratio exceeds a predetermined second rate change for at least a predetermined third time; and terminating the brine/slow rinse step based on said third detecting step.