Lagering Questions

[imark]

It'll contract as temperature decreases either way. Sucking in airlock content is probably more an issue of incorrectly filling it. The point really relates to pulling in air and specifically exposing it to oxygen at that stage. If you are concerned about that then you'd need to come up with a creative approach to avoid oxygen exposure at that point.

[molc]

Near the end of fermentation, empty the airlock and put a balloon on it. That will catch co2 and then as you cool your just sucking it back in.

Personally, I just have a low fill level and cool away with vodka in the airlock. If it gets in, no big deal.