What is the proper well system air pressure for the bladder tank?

What is the proper well system air pressure for the bladder tank?
Shut the pump off at the breaker box and open a hose bib to drain the pressure off. You may now set the bladder tank up for operation.
The pressure setting on a bladder tank is 2 PSI under the cut-in PSI on the control box. In other words, if the control box reads 20 PSI cut in and 40 PSI cut out the bladder tank will be set at 18 PSI **or** at 30/50 the tank will be pressurized at 28 PSI. Good luck, tom