One other thing I’ve learned in trying to calibrate pulses to water flow (in gallons per minute or milliliters per second) is the problem that can arise if you’re using a shallow well pump, and water table begins to drop because of extended drought and no rains. What eventually happens is that the water table drops, the pump starts pulling in a little air mixed with water, and it will gradually get worse until the pump runs completely dry and burns up the motor. A flow sensor will probably not detect this condition in a timely manner, because the internal paddle wheel of flow sensor still can be spinning to produce pulses even when it’s pushing air mixed with water. Your line pressure is dropping, actual GPMs are low but again, and you may have inaccurate flow data as the pump is overheating and water pressure is dropping off.