240v power at 10 amps will give you about 3 horsepower. You shut off pressure is about 130psi. If your surge tank builds up to 60psi. If you work 3.2 horsepower backwards at 130psi you get 42 gallons per minute. I know the pump isn't 100% efficient but something is not adding up. If it were 50% efficient that is still 20gpm. Most of these pumps should at least be 70% efficient. I went on lowes to look up the biggest submersible well pump I could find. It is a 1.5hp for wells up to 350 feet deep. Lets say you do 10gpm at 300 feet of static head (165 water column plus 60psi at tank level) that is only 3/4 of a horsepower. Lets say the pump is only 50% efficient so it needs 1.5 brake horsepower to run it (1,100 watts) it would only need about 4 to 5 amps at shutoff. Assuming you have this pump lets say you pump the well water into a regular non pressurized above ground tank (not into the pressurized tank) and only had to over come water column plus 10 feet (to the top of the above ground tank) then the pump would only need one horsepower if the pump was 50% efficient. 1 horsepower would need around 3 amps at shut off. You could always stick an amp clamp on it while its running and see how much power it draws.