Abstract: An arrangement for controlling the addition of liquid in the cleaning of containers, especially of milk tanks, has a circulating pump operative for circulating a cleaning liquid withdrawn from a lower part of the container and again sprayed into the container at a higher part thereof, a measuring path flanked by two measuring electrodes directly introduced into the measuring path and incorporated into the circulating arrangement, so that the continuous variations of the electric resistance of the liquid column flowing through the tubular measuring path during the circulation are sensed by the measuring electrodes and transmitted as signals to a control element which converts the signals to a further signal which actuates a closing valve arranged at a liquid inlet conduit.