The flow meter receives water directly from the pump's outlet. The reading of 100 (or 101 in pictures) on the panel meter represents 100% flow, as calibrated by myself when testing. When I adjust the pot that regulates the voltage received by the pump, the flow rate goes down, and the meter displays the percentage of the flow. At the lowest pot setting, I get 36% of flow, at which point the flow sensor trips a relay that turns on a loud buzzer.
I would like to thank Ebay for making this endeavor possible