I was just messing around on Ebay, and found these great oxygen flow meters. They are what they mount on the wall at hospitals to show how much oxygen you are on. They are cheap used, what do we care its not like we are breathing the gas in this case. Also they read in liters per minute from 0-10 lpm. This would suit most of our need and then you would just have a hose for in and out. instead of the big tube of water with a bottle. Not that there is anything wrong with this method I am just bringing in a new Idea. I am just wondering has anyone tried or played with this idea?