Running just one faucet (shower for instance) the water pressure fluctuates a lot, even with nothing else running, and the pump kicks on frequently. It will go up to 50-60 psi, then the instant the pump kicks off, it drops to 30. Hitting the pressure tank seems to reveal an area at the bottom with water, then air above it, then water, then air. Nothing comes out of the valve when water has been drained. Air did come out when it was full - no water was noticed to come out. Aqua Air V100. 12 years old.

So, does this sound like the tank needs replace? Can just the bladder be replaced?

Two well companies also suggested it could be some seal or gasket needs replaced in the tank itself (however they said if we opened the cap we would hear hissing that meant that part needed replace and we heard nothing). Also there is no wetness/water around on the ground near the tank.

Anything else we can do/check to make sure that it is the tank - hate to replace it then find out it isn't bad. Thanks!