I have done about 20 BIAB brew sessions so far this year and have made some nice beers, but my biggest frustration is cold crashing in my fermenter. The fermenter can suck up to about a half quart of sanitizer into the beer when I drop the temperature from around 68 degrees F to about 34 degrees F. I really don't want that much non-beer in my beer. I usually transfer 6 gallons of cooled wort into my SS Brewtech Bucket fermenter and attach a blow-off hose to a container of Star San solution inside my fermentation chamber (see photo). After fermentation is completed in a week or two, I drop the temperature to about 34 degrees F. In a few hours the sanitizer is drawn up half way up the blow-off tube and continues rising if I don't release the pressure inside the bucket. My dilemma is to either let outside air into the fermenter by releasing the vacuum pressure or let a large volume of sanitizer dump into the fermenter. Unless there is nothing wrong with either approach, then maybe I have nothing to worry about. The choice is either O2 or sanitizer in my beer. Or perhaps a third choice would be not cold crash in the fermenter at all, and keg it at 68 degrees and store the keg in my 35 degree keezer for a longer period of time. Any suggestions?