Method for operating a metering apparatus for dispensing pumpable media, in particular colour pigment preparations, in a metered manner, wherein the metering apparatus has an output device which is flow-connected to a plurality of canisters, wherein the canisters have each been filled or are each filled with a defined initial filling quantity of a medium which is to be dispensed, and wherein the metering apparatus has a control device by means of which a defined dispensing quantity of the medium is drawn from at least one of the canisters and delivered to the output device by means of a delivery device at defined times, characterized in that a current actual filling level is also ascertained and/or calculated by means of the control device depending on a dispensing quantity which is drawn from the respective canister, wherein at least one calibration sensor is arranged on the canister such that the said calibration sensor responds if the medium in the canister reaches at least one calibration filling level, which is already known and is stored in the control device, and transmits a corresponding sensor signal to the control device, the control device identifying the calibration filling level as the actual filling level and/or taking the said calibration filling level as the new, current actual filling level on the basis of the said sensor signal, in that a respective current actual filling level for the canisters is ascertained by means of the control device, for the purpose of monitoring the filling level and/or ascertaining the filling level, in such a way that the actual filling level of a canister, which actual filling level is respectively currently stored by the control device, is reduced by the value which corresponds to the dispensing quantity which is drawn from the canister, and then the value which is reduced by this dispensing quantity represents the new, current actual filling level and is accordingly stored, in that the control device compares a currently stored actual filling level with at least one prespecified filling level threshold value, wherein, if a new, current actual filling level reaches or falls below a prespecified filling level threshold value in the case of a canister, a refilling instruction is output and/or displayed, in that the canister is filled with a defined refilling quantity in the case of the need for refilling being ascertained by the control device, wherein the refilling quantity is detected by the control device and/or is transmitted to the said control device and/or is input into the said control device, in that the control device, after the filling process, takes, as the starting value for the current actual filling level value, a value which is made up of the sum of a refilling filling level value, which corresponds to the refilling quantity, and of the actual filling level stored last, and in that, if the filling level of the medium corresponds to the at least one calibration filling level, the at least one calibration sensor responds and transmits a signal to the control device, the control device identifying the calibration filling level as the current actual filling level and/or taking the said calibration filling level as the new, current actual filling level on the basis of the said signal.