[shibbs]

Before leaving for 3 days, I turned the temp controller down to 34 degrees for cold crash on 2 beers that have been fermenting 3 weeks.  Got home and when I opened freezer to rack into kegs saw that a significant amount of water/starsan from the bucket was pulled through the blowoff tube into beer, and the other beer had sucked the airlock dry.  I could see a stratification layer in the carboy, so tried to rack only beer below color change.  I'd like to RDWHAHB, but I'm worried about contamination and also lost beer.  For future brews, was this a bad practice?  I want to try a lager fermentation with my chest freezer, and avoid this from happening again.  Any feedback?  Thanks all.

[denny]

If you're cold crashing, then fermentation is finished.  In that case, you don't need a blowoff or airlock at all.  Just seal the containers.

[bluesman]

That is typical. Agreed with Denny's recommendation. As far as cold crashing with a three piece airlock...it is normal to suck the airlock solution back into the beer. You can switch to a Triple S airlock to eliminate sucking the solution back into the fermenter during cold crash.

[shibbs]

Thanks for replies... hopefully others won't make same mistake I did.  Oh well, next time I'll get it right.

[euge]

I wouldn't worry too much about it being infected either.

[wingnut]

Denny's comment is good..but I just keep the "minimum" water in the air lock when I am crashing and that keeps the water from being sucked in (both 3 piece and s style).  I also use star san solution in the airlock...so it kills th baddies it may have trapped during fermentation, and the slight addition of phosphoric acid is actually  a benefit by this time if it does get sucked in. 

Euge is right though, contamination should not be an issue.

Good luck!

[skyler]

I usually use a vented silicone bung for my already-fermented beers, whether cold crashing, lagering, or what have you.

[tschmidlin]

I usually use a vented silicone bung for my already-fermented beers, whether cold crashing, lagering, or what have you.

Same here.  I also use them when cooling wort in the freezer after the chiller gets it to 78F

I'm leaving them on for primary for the first time ever.  I don't think I'll be doing it again, I'm not confident they actually burp the way they're supposed to and the pressure that builds up can change the way the beer ferments.

[tom]

Or if you want an airlock, the S-shaped airlocks work in both directions.