Abstract: The invention relates to a method for controlling a pumped sludge flow by throttling the suction side of the pump and to a device for use in the method. The device having an inner member with an outer member so fitted around it that the inner member and the outer member can be moved in relation to each other, and inlets provided in either the inner member or the outer member or both so that when the inner member or the outer member is in one extreme position the inlets are fully closed and when it is in the other extreme position the inlets are fully closed, and a channel which leads to the suction side of the pump fixed to either the inner member or the outer member so that when the inlets are open, liquid flows from the surroundings through the inlets into the channel and thence into the pump.