For CO2 in a sub here is my list for my I-400:
Palmer Rock the boat Regulator
Small 12 or 16 gram CO2 cylinders
Manifold in 2 saddle tanks (on either side of my Battery room etc
that connects 2 tanks together.
One servo controlling 2 poppit valves
push one way and co2 blows into tanks (open at bottom)
push other way and tanks vent to top of ship.
hope that helps


hope that works and helps a little
Bryan