I read where that soft starter thing only works from 1.75HP to 7 HP. So it would not work with a 1/2HP pump.
As per the Franklin Aim manual....
"Reduced-voltage starters may not be required if the maximum recommended cable length is used. With maximum recommended cable length there is a 5% voltage drop in the cable at running amps, resulting in about 20% reduction in starting current and about 36% reduction in starting torque compared to having rated voltage at the motor. This may be enough reduction in starting current so that reduced-voltage starters are not required."
So if you run 100' of #14 wire to a 115 Volt, 1/2HP pump it will act like it has a soft starter. It would take 400' of #14 wire to make it work for a 230 Volt in 1/2HP.