Originally Posted by johnnybrew
Maybe I am answering my own Q... I use three piece airlocks. I guess if I used the single piece for the cold crash it would bubble in reverse? Would that do the trick? It is still going to suck air through the fluid chamber. Will it get cleaned up by going through my vodka?
Well, I will answer more fully.
Since the suckback happens so late in the process, there is a nice pocket of CO2 waiting for your unsuspecting sucked in air when it gets in your fermenter. It will continue to blanket the beer while the air waits on top. They will diffuse eventually, but slowly (so dont cold crash for several weeks).
Oh, and nothing bad can live in the vodka.