I have noticed a potential problem with my airlock during the cooling cycle of my fridge, and I could use some advice...
Recently, I purchased a small wine fridge to control the temperature of my fermentation. I could not afford a temperature control unit, but I found that at the lowest setting the internal temp was around 65ish. Also, the door is tinted glass, which allows me to watch the fermentation without having to open things up. A couple of weeks ago, I started a new ale, and by now, the fermentation is essentially complete (i.e. no bubbling in the airlock). Anyway, I checked on the beer today during the fridge's cooling cycle, and I noticed that the change in temp had caused a partial vacuum in the carboy. This caused the liquid in the airlock to get sucked all the way up to the top of the inner tube... I don't know if any liquid got into my beer, but if it did, I am worried about bacteria/mold getting sucked into the beer.
Has anyone else had this problem? Any suggestions? (I wonder if this is a common problem for people who make lagers and slowly lower the temp on their beers from fermentation to lagering temps... Although there must be some diffusion of air through the water into the carboy over time, but I think this is slow.)
I was thinking to myself that some sort of two-stage airlock (with a one-way valve before the bubbler) would really do the trick... Has anyone used anything besides a blowoff hose or the airlocks that B3 sells?
Any help is most appreciated. Thanks.