Abstract: In an arrangement for regulating the moistening solution mixture for use in an offset printing press, a tank is provided with two separate spaces, one for the moistening solution mixture and the other for a moistening solution additive. A conduit system containing various regulating devices is connected to the tank for regulating the introduction of the additives into the mixture and for the supply of the solution to the printing unit, a crystal sand filter is located in the conduit system for filtering the mixture and a pump, associated with the filter, directs a part of the filter mixture to the printing unit and returns a part of the mixture to the tank. A flow measuring electrode is arranged in the conduit system and is operatively connected to the regulating devices for controlling operation of the arrangement.