Reverse pressure??

[brewkinger]

I placed my fermenter in the outside entrance to my home to cold crash it for a couple of days before bottling (first time I have done this)

I noticed today that the pressure inside the carboy dropped enough that I now have reverse flow into the airlock.

Nothing too vigorous, but I am wondering if this is normal?

I am thinking that I am OK because the starsan/water mixture will not hurt the beer if it in fact did get inside.

 

[jesserizzo]

Exactly why we use sanitizer in the airlock instead of plain water. It will be fine.

 

[unionrdr]

It's a partial vaccum caused by the temp drop. The starsan & water mix won't hurt anything. That's why I use cheap grocery store vodka in my airlocks.