Brewed a Northern Brown extract kit on Saturday, hit the target OG. Pitched yeast a little cold (63F), but activity was in full swing by yesterday morning. Woke up this morning (Monday) to find that there was beer pushed out the top of the airlock - not a full on gusher, but significant.

The top of the fermentation bucket was bowed, so I cracked the lid a little to alleviate the pressure. Is there anything else I should do besides re-sanitize the airlock and replace on top the fermenting bucket?


2 Answers 2


The best is when so much pressure builds up that the airlock is shot to the ceiling and your closet is splattered in fermentation goo.


  1. use a 6.5 gallon carboy for 5 gallon batches -and/or-
  2. use a blow-off tube (examples here)
  • Thanks for this. It mirrors the advice I got on Twitter this morning. I am in a 6.5 gallon fermentation bucket, so I added the blow-off tube.
    – zy1125
    Feb 15, 2010 at 15:26
  • 1
    had the same thing happen...the top ended up blowing off so i had a good old fashion open fermentation for a few hours....side note - no contamination and final beer turned out great...
    – Arlo427
    Feb 15, 2010 at 21:36
  • I experienced this phenomenon once about 18 years ago. It was quite a sight to behold. In fact, I can't even begin to describe all the places I found expelled wort over the following several weeks. On the upside, hops do make a great air freshener, but not something you ever want to have happen. That's why I always use a blowoff tube for primaries. Never had one of those get out of control.
    – Bill Craun
    Sep 12, 2011 at 14:55
  • Bubbler rule # one: Never have the 'bug cover ' in place while active fermentation is happening. The risk is having to use the mop on the ceiling, hehe. The bug cover is the thing with the tiny holes in it that goes on the very top.
    – Dale
    Jun 27, 2012 at 22:04

To answer your second question - "Is there anything else I should do besides re-sanitize the airlock and replace on top the fermenting bucket?" - No, that's sufficient, assuming your krausen isn't still reaching the airlock hole. If the krausen has backed off, just re-sanitize and re-insert your airlock. Your risk of infection during the rapid primary phase is low due to how much CO2 is being generated and forced upward. Airborne beasties can't really settle into the brew. If your krausen is still reaching your airlock hole, however, then yeah, use a blow-off tube.

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