Will the air pressure in a pressurized well tank equal the water pressure?

This is for a system that is pressurized with water (ie, not empty of water). When you take an air pressure reading on the tank, should it read equal the water pressure in the system? Thinking back to my old physics class, i thought they should be equal. I'm just curious if my air gage is off from my water pressure gage by a few pounds...both are high quality and fairly new gages so I was surprised to see a difference.

 

The difference will be small, less than one psi. There will be a little height difference, and there may be a little tension on the diaphragm. But close.

Take your air gauge to a tire store and ask them to compare to their gauge.