Looks pretty cool, the self-calibration routine is very nice too. My only worry is that rapid changes in pump speed might cause extra mechanical stress or wear

Looks pretty cool, the self-calibration routine is very nice too. My only worry is that rapid changes in pump speed might cause extra mechanical stress or wear on the pump, but I have no data to back that up. I've just heard that water pumps sometimes behave in counter-intuitive ways - e.g: sometimes running at a higher speed is better for longevity than a lower one.