Given the alternative of a PTO pump vs an Electric, always go with the PTO. The electrics are handy but they just dont have the guts to put out volume and pressue that you would like to have. The PTO pump will give you great mixing with the bypass that you wont get with an electric.

There are great directions that are simple online to calibrate. As stated, you need to know speed and flow rate...flow rate is a function of your pressure. Most nozzels do best in the 25 to 30 pound range. Over 30 you develop too many fines.