So I decided to try my luck with a paintball CO2 tank. It was relatively cheap: under $60 ($35 for the tank, $10 paintball on/off valve, $10 needle valve, $3 for the barbed adapter). I set it all up tonight and was a bit tough to get calibrated correctly but I finally got it going with a good stream of CO2. A few hours after set-up I heard a loud hissing and found the tank leaking at the on/off valve attached to the tank. I reattached it and it did the same thing 15 minutes later.
I'm wondering if anyone has tried this before or is familiar with paintball tanks. How tight does the connection to the tank have to be? Is there supposed to be a gasket that I'm missing? Or is this set-up incorrect and doomed to fail from the start?