On all pumps, flow rates may be altered when operating or at rest. On the “Q” line this is done by turning the Flow Control Knob which moves the flow rate indicator along a fixed 20 unit scale linearly calibrated “10-0-10”. The “10” equals 100% flow rate in that direction, “0” equals zero flow. To improve the fine adjustment of the flow rates on the “Q” line, there is an optional Dial Indicator Kit Q485 which provides for 1000 discrete settings. The “RH” line flow adjustment is accomplished by turning an easy-grip Flow Control Ring graduated in 450 divisions from 0 to 100% flow.