Last weekend I brewed my first batch of beer. I ordered the kit back in April because there was a Groupon and stuck the yeast in the fridge until I needed it.

Its been a week and I haven't seen any bubbling in the air lock, so I was thinking the yeast didn't make it. However there is a lot of pressure in the fermenter because when I touch the lid I can feel that there is gas in there, and today I saw that the top was not fully locked in anymore. So now I think that the air lock is just not working.

I went to YouTube and saw a video for the airlock that I have. It turns out I didn't put on all of the pieces. I have a 3 piece airlock (http://www.midwestsupplies.com/airlock-3-piece-type.html) but didn't put the circular lid part on.

Is this a big problem or by putting the top on now everything will be ok? I figured the water was there to prevent the wild yeasts and bacteria from getting in there. Is that a safe assumption?

Is this why I don't see bubbling or is it more likely that the yeast didn't last that long, even though it was in the fridge?

  • I'll leave the long answer to someone with more knowledge and time on their hands, but the airlock is used to keep oxygen out of the tank - otherwise no fermentation will take place (With oxygen, alcohol is not produced). This also of course keeps bacteria out.
    – Max
    Aug 27, 2011 at 17:29
  • I do have two of the pieces and the water. So it seems as if oxygen cant get in. Looking at it now, the cap has many holes in it to so the gasses can get out, but that also allows oxygen to get into the lock, above the water. The water should prevent it from getting into the fermenter. The only problem I can think of is that the cap allows it to fill up with gas and only allows little get out at a time, which prevents the oxygen from touching the water. As noted in my question, this is my first batch, so I'm just thinking out loud right now.
    – JayUnt
    Aug 27, 2011 at 17:36
  • 4
    @max, There are many breweries around the world that use open fermentors. These are usually large rectangular tanks that have no top to them. The surface of the beer is exposed to the air, yet fermentation happens. You can ferment without an airlock just fine.
    – brewchez
    Aug 27, 2011 at 21:49
  • 1
    actually oxygen is helpful in primary fermentation and a good swirl before airlocking is a trick that enhances the fermentation. I'd check the final gravity, or just taste it :-)
    – drj
    Aug 27, 2011 at 22:30
  • @brewchez True, my comment was incorrect. :) But it is true that with oxygen, alcohol is not produced, since the yeast would use ordinary cellular respiration. In a tank or indeed fermentor the CO2 output would be large enough to shield the liquid, atleast during initial fermentation. If I'm not completely mistaken.
    – Max
    Aug 28, 2011 at 12:24

3 Answers 3


Don't worry about this too much. What you don't want is lots of oxygen coming into contact with your wort which can lead to the oxidation and spoiling of your batch. However, this doesn't sound like it was a problem in your case. The main problem with a blocked airlock is that it can be dangerous due to a build-up of carbon dioxide which can (in extreme cases) make things like glass fermenters and bottles explode.

Did you look and see any evidence of fermentation in the first few days of the brew (I am assuming that there was because you mention a pressure build up)? You can also measure the specific gravity with a hydrometer to see if fermentation has taken place.

  • I opened the bucket up and there were a ton of bubbles and "foam" on the top of the liquid. I also measured the gravity again and it was a lot different compared to the OG, 1.012 compared to the OG 1.042. I guessing it wasnt bubbling because of the cap of the airlock. I guess i shouldn't have worried :) Thanks for your help.
    – JayUnt
    Aug 27, 2011 at 18:39
  • It's likely that it wasn't bubbling because the bucket wasn't properly sealed. This has happened to me several times. I just RDWHAHB, and the beer always comes out fine. Aug 29, 2011 at 10:52

You don't need the cover on the three piece airlock for it to work right. If you weren't seeing bubbling I challenge that the lid wasn't on the bucket tight enough and the gas was escaping else where. Or the majority of fermentation happened when you weren't paying attention. If you ferment to warm that scenario is totally conceivable.

I suspect your beer is fine. (aside from a hot ferment)


After a week you should see a krausen, off-white foam on top of the liquid, or the remains of one - dark brown bits stuck to the side of the fermentor above the level of the beer. If you see that, then the yeast are fine.

The cover on the airlock is not essential - the airlock still provides a water-barrier without it. The cover may help slow down evaporation of the liquid in the airlock, (and in my case, keep out a 2 year old's inquisitive fingers) but otheriwse, leaving it off makes little difference - fermentation will happen fine without it.

With some brews I don't get any airlock activity, so I look for a krausen as a sign of fermentation. If I don't see one in 3 days, then I consider pitching new yeast.

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