Negative pressure in cold crash

[pazu]

Hi,
Last night I mini-kegged 5 gallons from cold crash and I am sending another 5 into cold crash today.

The issue I'm having is that the temperature reduction from my ale ferment to cold crash temps, is resulting in liquid being sucked back up my blowoff hose. It gets about 1/2 way it seems, then when I want to be safe & get rid of that liquid in the hose by lifting the hose out of the blowoff liquid container which has iodophor in it, the liquid rises in the hose instead of falls. It's hard to see but I don't think I've let any get into the carboy. I don't know what iodophor actually tastes like and don't want to find out, so I can't tell whether it's in the beer or not, by taste.

How do I prevent the negative pressure created by the cooling shrinking atmosphere in the cold crashing carboy, from sucking liquid back up into the carboy?

Must I simply do cold crash only with aluminum foil over the top of the carboy?

My next 5 gallons is in a pail, not sure how I can put aluminum foil over a pail grommet hole !

Thank you for any suggestions.

 

[Ozarks Mountain Brewery]

treat the cold crash just like you would put anything in the fridge, you want it to be sealed so put a solid plug in during the crash, assuming your not still fermenting

 

[LarryBrewer]

I remove my blowoff tube and fit with an airlock. That means it will bubble in reverse during a cold crash. If you are really worried put vodka instead of sanitizer solution in the airlock.

 

[DanC]

I too learned my lesson the first time I cold crashed and sucked in the airlock liquid. I now just plug the hole.

 

[pazu]

Thanks guys I had to transition from airlocks to handle over-foaming. I have an airlock on it now with foil over that. Next time I will be ready for this situation!

I had thought it would be better to avoid disturbing the setup until I was ready to rack it. Now I know better.

Would've been a lot easier carrying the carboy to the fridge, without carrying the tubing and blowoff vessel as well...

Vodka! Good excuse to have it around. Somehow these latest brew batches are treating me so well compared to store bought beers. I bought some IPA recently when I had run out of my own, & it made me feel ill. I'm just sticking to my own brews from now on, the yeast know and like me I think, plus it is way cheaper.

I read recently that a human 'biome' by cell count, is only 20% human. 80% of the rest of 'us' is bacteria, yeasts, other foreign cells. It said that practice of medicine is only beginning to realize just how relevant that 80% non-human life is, to our overall health. I guess in a way, if we brew, then we are what we brew!

 

[Nosybear]

I like the thought that we are what we brew.