Seems like my center ballast bag on my 02 X-star gets a lot of air in it somehow. I fill it until it runs out the over flow then lift the ski locker door to see a huge air bubble in it. Upon emptying, if I pull the bag out and squeeze all the air and water out, it seems to fill right the next time, but over the next few trips it accumulates a bunch of air again. Any easy fix to this? Thanks.

put a one way valve on the overflow and everytime you pump it out, you will pull all the air out and pull the bag completely empty

How does all that air get in there to begin with? Does that much air get forced through the overflow while trailering or something?