Cold crash sucks in air

I placed my Imperial stout in the freezer yesterday to start the cold crash. When I came home after work I noticed that the airlock has less fluid in it then when I put it in the freezer. I believe that the temperature change caused air to be sucked into the bucket. Does this pose an oxidation problem. Is this something I need to try and prevent in the future, and if so how?

I use a blow off tube and stick the end in a jug about half full of starsan. I make sure the end is NOT in the starsan and then cover with foil. I doubt the small amount of oxygen drawn in would even make it to the beer since it’s still has a blanket of CO2 on top.


I usually just put a piece of foil over the top of the carboy and just not worry.

It’s sucking in starsan, so no air is getting in. I wouldn’t worry about it. That’s why we use sanitizer in the air lock.

However, you can get a solid bucket lid to replace it with when you cold crash. I think Denny does this.

I don’t really cold crash, just because I don’t know that it makes all that much difference other than getting a head start on carbonating in the keg. The yeast and haze takes weeks to drop out unless you’re going to be fining the beer.

This^^^^. The beer is done fermenting. Why are you still using an airlock? Just seal the fermenter before crashing.

I just leave the airlock there because I never thought to take it out. Guess that’s a lesson learned for the future.