Abstract: An improved method and apparatus includes operating a multistage supply pump to induce a flow of the cleaning solution through one or more supply conduits to one or more dispensing devices. The multistage pump contains a plurality of impellers which are driven by a variable speed electric motor. The speed of operation of the multistage pump is varied as a function of variations in the fluid pressure in a supply conduit. A single stage return pump induces a flow of solution from the receptacle. A total organic carbon analyzer is utilized to determine the concentration of organic carbon in a return flow of solution from the receptacle. The electrical conductivity of the return solution is measured and is applied as a threshold value to initiate use of the total organic carbon analyzer. An acoustic sensor is utilized to sense variations in operation of the cleaning apparatus.