A method of controlling the flow of reprocessing fluid through an instrument having at least a first channel and a second channel, during an initialization procedure, wherein the first channel is defined by a first value of a parameter and the second channel is defined by a second value of the parameter, wherein the parameter comprises a flow resistance value of the respective instrument channel, said method comprising the steps of: initializing a pump in fluid communication with a reprocessing fluid source to begin an operating cycle; supplying the reprocessing fluid to a first fluid circuit comprising a first valve , wherein the first fluid circuit is in fluid communication with the pump and the first channel; supplying the reprocessing fluid to a second fluid circuit comprising a second valve , wherein the second fluid circuit is in fluid communication with the pump and the second channel; modulating the first valve to limit the flow of reprocessing fluid through the first channel, wherein the amount in which the flow of reprocessing fluid is limited is a function of the relationship between the first value of the parameter and the second value of the parameter, whereby the reprocessing fluid flows through the first channel and the second channel when the pump is initialized; and modulating the second valve ; wherein said step of modulating the first valve comprises modulating a first variable valve orifice , and wherein said step of modulating the second valve comprises modulating a second variable valve orifice; wherein said modulating step comprises limiting the flow of reprocessing fluid through the first channel such that the pressure of the reprocessing fluid flowing through the first channel is the same as the pressure of the reprocessing fluid flowing through the second channel. initializing a pump in fluid communication with a reprocessing fluid source to begin an operating cycle; supplying the reprocessing fluid to a first fluid circuit comprising a first valve , wherein the first fluid circuit is in fluid communication with the pump and the first channel; supplying the reprocessing fluid to a second fluid circuit comprising a second valve , wherein the second fluid circuit is in fluid communication with the pump and the second channel; modulating the first valve to limit the flow of reprocessing fluid through the first channel, wherein the amount in which the flow of reprocessing fluid is limited is a function of the relationship between the first value of the parameter and the second value of the parameter, whereby the reprocessing fluid flows through the first channel and the second channel when the pump is initialized; and modulating the second valve ; wherein said step of modulating the first valve comprises modulating a first variable valve orifice , and wherein said step of modulating the second valve comprises modulating a second variable valve orifice; wherein said modulating step comprises limiting the flow of reprocessing fluid through the first channel such that the pressure of the reprocessing fluid flowing through the first channel is the same as the pressure of the reprocessing fluid flowing through the second channel. <EOS>