I have a well water system that goes about 660 feet deep. The pump is under ground and then it feeds a 50 gallon pressure tank and charcoal cylinder type filter. For some reasons I noticed my sprinkler system had very little pressure. I went to look at the tanks and although pressure gauge stated 60-70psi, the tank itself was filled all the way to top of the tank. Normally there is more air than water in the tank, so I assume this is my problem. How do I reduce the water level in the tank and why did this occur?

Is this a bladder tank (usually a painted tank) or a pressure tank, (usually galvanized unpainted tank)?