I had some minor blow-off enter (and exit) my airlock during the most active part of fermentation. The krausen has since gone down significantly, and there is no worry of the airlock getting clogged.

The vodka, however, has turned a light brown due to the blow-off that entered the airlock.

Should I be worried about this? Should I remove, resanitize, and refill the airlock? Or is the trade-off of introducing oxygen into the carboy while doing this a greater concern?

3 Answers 3


Introducing oxygen is not a concern at all at this point. That's a bogeyman that's way exaggerated. You could probably leave it without problems, but I like to remove it and clean it when that happens to me.


Good answers are already posted to answer the question. But one thing that isn't mentioned is the ways to avoid this from happening in the first place:

  1. If you brew a 5 gallon batch have your primary fermenter have at least a 6.5 gallon capacity. Thereby allowing enough headspace so that active yeast growth and CO2 production will not blow out your airlock.
  2. If you are brewing a high gravity beer or don't have a larger capacity carboy. Place a sterilized hose into the rubber stopper on the top of the carboy and place that into a container of sterilized liquid which is placed at a lower elevation relative to the stopper in the top of the carboy. Thereby allowing a sterile blow-off location saving you the trouble of a mess outside your carboy. Then after the active fermentation has finished affix a standard airlock.

It never hurts to be overly cautious with sterilization. That is why I always use sanitize on the mouth and top of the carboy and my hands before pulling an airlock if the beer is not finished out.

  • 1
    I think the jar of sterilizer that the blow-off tube terminates in should be lower than the carboy of fermenting beer. If it's above the carboy you run the risk of siphoning the sanitizer into the carboy. If the temperature of the beer drops, enough suction could be generated to start the siphon and the height difference will keep it sucking. Jan 9, 2012 at 20:56
  • 1
    Interesting point never thought of that. Also I guess if you had a large enough pressure differential due to weather could also be an issue. Someone else at my local homebrew store was also worried about drain-back from the hose as well. I have never had a problem with this, but I do see your point I am going to edit my post. Jan 17, 2012 at 21:16

Introducing oxygen is nothing to be concerned about at this point. I'd say its safe to go ahead and clean it. Just make sure to sanitize it and anything else you touch that interfaces with the carboy, before you put it back. Some people recommend spraying sanitizer on the mouth of the carboy too.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.