Dude-
Dont bid on it anymore. If you don't know what you are doing don't buy the tank. My dad scubas, and has taken lots of classes on everything about compressed air, so I bought a fill station and he fills my tanks.
You wont really get any fills from a tank that small with that low pressure. First of all, 2250 is not much air to play with, depending on your tank. I can just barely squeze a day out of my 3000psi 88 tank.
And the pressure will drop big time when you fill it. With a 68cu in tank you will probably lose 400+ psi in the tank every time you fill it. So, if you fill your tank(paintball one) at 2250 the first time, the next time you fill it youy will probably get around 1900psi, and so on...
The only way that having your own scuba tank saves a lot of money, is when you can get your scuba tank filled for free.
