I have the 400lb sack (I think) in my ski locker on my 20v, but I'm sure every time I fill that thing up it's half full of air, so I doubt I'm getting the full potential out of the bag. I usually just fill up another bag in the walk way on the floor, but I'd like to get every bit of water in my ski locker bag as possible. Anyone figured out a way to vent that bag so I can release the air out of it?