I get what your saying. BUT!!! this is like the old debate "Air lock or no air lock". what it comes down to is try it, if one way works and the other way doesn't or vicea versa, and it's all with the brewers comfort level. Me I have no worries because if I am cold crashing I'm doing it in my lager chamber and it is a chest freezer the is always filled with CO2 ( I feel) and No I do not use air locks either just (in my eye's) no need. Now if these beer's are for entering comps or the drive for Ninkasy then maby these are things that the brewer would want to do??? Cheers Brotha.

If you're crashing in your ferm chamber, you would be pulling in greater proportion if not all CO2, but if it is surrounded by ambient air, it is going to be pulling in O2 as the gas in the headspace contracts. That IS what happens as gasses get colder, I don't feel there's a debate here. As for airlock or not, again if it is actively fermenting there will be CO2 coming out, but as it slows and stops, O2 would be more able to diffuse into the headspace of the fermentor, which is why I feel that airlocks are necessary if the beer is going to be sitting for any amount of time NOT actively chugging along. Just my view on things.

Ok then what would be worse, pulling in vodka, star san, water through your air lock, or just pulling in air? because after the fluid gets pulled into the fermenter then all that's left is air. Either way you go your still going to be pulling in amb air.