First search for this..Where can I find this adaptor. That actually sounds really helpful.
If I get them online are they just called paintball tank o rings?
Only one I could find..Trinity Paintball CO2 Tank adapter to CGA 320 Industrial keg aquarium upgrades
You'd take the adapter off your regulator and use a plastic seal between the 2.
As to the o rings they look to come in different sizes but they are everywhere so to speak.
some are metric, some US..
What a bout where you bought the tank?
Brand and model?