Re: Low well pressure.
Bladder tanks also have a schrader valve (Air stem just like on your tires on your car) There should be a posted pressure and I know it only takes a few pounds (it should be posted on the tank) and a bicycle pump works fine.
Not likely Bob, on the 'few pounds. A bladder tank, dry (no water) needs two PSI below the pump on setting. If the switch is set to turn on at 40 psi and turn off at 60 psi, the dry pressure tank needs 38 lbs of air pressure (2 psi short of pump turn on pressure)
Most modern pressure switches are preset to operate between 40 and 60 lbs. They can still be purchased to operate at 30-50 psi. There is no difference between the switches, just what they are set at from the factory. They are also adjustable in the field, however too many people monkey with then who have no understanding of how it should be done and never re-balance the pressure tank to boot.
You can only measure this precharge pressure when the system is drained down. If the above scenario was the case and the tank pressure was substantially less than 38 psi, you would be there all day trying to pump it up with a low volume bicycle pump.
If the tank is of the no bladder type, then all the above still holds except you want your precharge at 5 psi below the pump cut in pressure.
Non bladder tanks will need periodic recharging as they do not seperate the air and water in the tank. As such, the water will slowly absorb the air charge and deplete it.
A low precharge in either style tank can be responsible for low pressure in the home. When the well pump is at rest, it is that precharge pressure that pushes the water into the home, not the pump itself.
As an added note, there should always be a shut off valve, on the line to the house, after the pressure tank. This will allow you to shut the water off to the house without having to shut down the well pump and drain the system.