Like JZ and Palmer always say. "Bacteria doesn't fall up". Why use air locks, I have only used tin foil for the last 2 years.
What do you do after fermentation has completed? I understand there is residual CO2 coming out of solution, but what about if you cold crash a beer? Couldn't that method lead to oxidation?
There should be a constant off gassing (verry slowly) of CO2 so UNLESS you are adgitating the carboy constantly there SHOULD be no worry of O2 getting into solution, or verry little. Now if your going for Ninkasi or your looking to open a brewery maby this is something you should worry about, " Don't worry have a homebrew" Charlie Papazian