A method for managing deposits within a pump mechanism (81) is provided. Fluid suitable for dissolving, diluting or otherwise disengaging deposits which have accumulated on the internal working surfaces of the pump is brought into contact with the mechanism. The performance of the pump is monitored and this data is used together with process data received from, or associated with, a tool (83) being evacuated by the pump to calculate (80) fluid flow characteristics which are required to compensate for the accumulation of deposits on the internal working surfaces of the pump. Fluid is then introduced (2, 84) into the pumping mechanism in accordance with the calculated fluid flow characteristics.