Only 2 reasons to ever look at your airlock

Lots of beginners make this mistake so I am definitely not pointing my finger at any one particular person. This is just a tip for beginners.

Only 2 reasons to check your airlock:

1) To make sure it hasn't blown off. In that case blow off tube needed.

2) To make sure it's got the correct amount of liquid in it. In that case, add liquid as needed.

Airlocks will show you visibly when your beer is in it's most active stages. When not in the most active stages, you look, your attention span is no longer than 60 seconds while you are just staring at it. Oh, I see no activity. Look for another 60 seconds. There could be an hour between bubbles!!! And you might blink and miss it!!!

AIRLOCKS DO NOT TELL YOU WHEN FERMENTATION IS COMPLETE!!!

Tell your friends, pass around this info.

You neglected the beauty of seeing little bubbles.

You forgot number 3.

To smell your brew.

I use mine to watch the tiny bubbles. The first time I think I even giggled like a little girl.

darrenbrews said:

I use mine to watch the tiny bubbles. The first time I think I even giggled like a little girl.

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Only the first time?

Number 3 is to see how far apart the bubbles are coming. If there more than a minute apart then its time to rack.

johns said:

Number 3 is to see how far apart the bubbles are coming. If there more than a minute apart then its time to rack.

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The point of this thread is that this notion is incorrect.

If you have a high pressure front come in or your beer is cooling, it could stop offgassing but not be done.

When you first pitch your yeast the airlock bubbles less than once per minute and it is not done.

As soon as it is done actively fermenting it often stops offgassing and is also NOT done.

tackett said:

You forgot number 3.

To smell your brew.

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You can smell with your eyes?

johns said:

Number 3 is to see how far apart the bubbles are coming. If there more than a minute apart then its time to rack.

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Confirmed by stable hydrometer readings that Final Gravity has been reached.

johns said:

Number 3 is to see how far apart the bubbles are coming. If there more than a minute apart then its time to rack.

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Ummm. Not for this guy. That's what hydrometers are for.

flars said:

Confirmed by stable hydrometer readings that Final Gravity has been reached.

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Fair enough.

You forgot to insure you put it in. Yup been there done that

tx-brewer said:

You can smell with your eyes?

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Can't everyone?

After it stops bubbling then its time for a reading, That's, the reason for looking at an airlock

#3 - when drinking the airlock vodka

I like this post, because my first batch's airlock went like crazy for 48 hours and has gone completely dormant today. I have looked in on it a few times hoping to see a bubble but no joy. I'm relaxed, and I'm not worrying, but it's great to get the reassurance!

huh...and WHAT would be the reason to write or read this thread??
Hasn't Revvy already written the same thing a thousand times.

For the less pompous or those that don't ride a high horse....the airlock is a nice indicator of activity...not conclusive, but a nice indicator. If you have a good sealed closed system...it is a fairly reliable indicator.

pwkblue said:

huh...and WHAT would be the reason to write or read this thread??
Hasn't Revvy already written the same thing a thousand times.

For the less pompous or those that don't ride a high horse....the airlock is a nice indicator of activity...not conclusive, but a nice indicator. If you have a good sealed closed system...it is a fairly reliable indicator.

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I didn't feel like the OP was being pompous or a know it all. Sure the info isn't anything new and has been posted here many times. It's still not a big deal dude there's no need for the insults. Take that talk to the debate section.

I'll also point out the person that posted right before you found this thread reassuring. That alone makes the thread worth it.

pwkblue said:

the airlock is a nice indicator of activity...not conclusive, but a nice indicator. If you have a good sealed closed system...it is a fairly reliable indicator.

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a good example where it's not: my air locks in a rubber stopper always bubble. My air locks in a carboy cap frequently do not. The problem is most people coming here with "it's not fermenting", assume they have a closed system, and overwhelmingly more than likely do not.

That said, I'm not sure why a solo past on the topic. This is only one of a dozen questions that get asked multiple times in the same day without a search first.

freisste said:

The point of this thread is that this notion is incorrect.

If you have a high pressure front come in or your beer is cooling, it could stop offgassing but not be done.

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Confirmation: 20 days ago I brewed an American ESB with Windsor yeast. Airlock activity was pretty steady for about 36 hours. By day 5 it had stopped. Because Windsor is a slow/low attenuator, bumped the temp a degree a day until I hit 69, no real airlock activity. On day 11 I took a sample, 1.020. On day 13 I took a sample, 1.020. Day 14 I dry hopped, and returned it to a 70 degree environment. It sat calmly for three days. Last night I couldn't sleep and got up at 3AM and went to my office only to find the airlock on my AESB popping off fairly frequently. "Oh great!" I thought "I got an infection?!" But, I didn't mess with it. Finally got back to sleep at 5, back up at 7:30 to find slight airlock activity.

Worked at home today, by 11 the airlock had stopped. Figured I'd check the nearest weather station for their previous 24-hour reports. We had an overnight drop in pressure of over an inch (to 28.2!)! Now that the pressure has stabilized there's no more airlock activity.

Will check the gravity again tomorrow before starting cold crashing, but am pretty certain it will be 1.020/1.019.

I like to use the bubbling of the airlock, compared to visible fermentation activity and krausen, to get a very general sense of what is going on.
I find it useful but not the gold standard for measuring fermentation activity.

**edit -- change compared to to also accounting for

kroach01 said:

I like to use the bubbling of the airlock, compared to visible fermentation activity and krausen, to get a very general sense of what is going on.
I find it useful but not the gold standard for measuring fermentation activity.

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Yes, could be just one of many, many factors to look at, but nothing to base a decision on.

I watch it for entertainment, especially when it slows. I'll watch the bubble grow under the hat... getting slightly bigger.... come on baby, you can do it... *bloop* YEAHH!!!!!

Then wait for it to happen again.

Anybody ever almost been late to work because you were distracted watching your airlock? I have.

If you don’t care to seal your fermenter, that’s fine. If you don’t care to disseminate the information that an airlock provides, that’s fine. But please don’t disrespect those who do.

I've made a lot of batches of beer. A lot. I can say with certainty that with my equipment the airlock is definitely a good indicator of fermentation. I use better bottles and carboy bungs (not stoppers).

I think buckets might be harder to seal, and also rubber stoppers might not seat properly in carboys. In those cases, you won't see bubbles, and the airlock won't be a good indicator.

I'll go ahead and agree with the BobbiLyn in that the best way to know your beer is done is with the hydrometer. But for many (most), the airlock works fine.

I think this has become dogma around these parts: That airlock activity doesn't mean anything with regards to fermentation.


Look, I get the Sentiment and intent: to limit the number of newb posts about "my airlock no bubbles!"


But repeating it like it is scripture is just as misleading, IMO, as telling people to use it as their only tool (like instructions say).

CO2 is one of the byproducts of fermentation. The airlock is a crude way to gain insight into this activity. It is by no means perfect and it is not foolproof, but to suggest that it isn't a tool is taking a good idea (teaching newbies to use the more effective tool: A hydrometer) to an irrational endpoint.


My point being that if you have a good seal, if fermentation is active, you will get CO2 production, all things being equal.

Temperature changes can alter this (as rising temps will cause outgasing), as can changes in atmospheric pressure (can also cause outgasing).

No bubbles when it definately should be bubbling can also mean things: Bad seal, low temps/inactive yeast - it is potentially worth investigating. And I think that is the point: If you're not seeing bubbles and you think you should be: start looking at other metrics. What is SG? what is temp? Do you have a sealed vessel?

But saying that "the airlock does not indicate fermentation" is a big dogmatic backlash to bad instructions that tell newbies to rack or bottle based on airlock activity.


There is a lot of evidence we can use to judge fermentation: SG Readings, Krausen, time, smell, appearance of beer, temperature.... AND YES: Airlock activity. Each piece of the puzzle gives an incomplete picture of what the state of fermentation is - the more data points used, the more complete and accurate the conclusions drawn from that data can be.

I like looking at my airlocks for the soothing, hypnotic effect of the bubbles. It's very calming. Combine that with the aromatherapeutic aspect of fermentation (airlock sniffing) and it's like a home spa treatment for brewers.

That one was too easy. I was thinking: 1. Make sure it has liquid and 2. that the liquid is not beer. Same Same. I also agree with passedpawn though, but only 5 out of 6 of my bucket lids produce air lock activity.

Airlock activity in the first few days is indication that fermentation; however, lack of airlock activity is not an indication of no fermentation. This question does come up a lot and I always answer with the "depend on the hydrometer" answer if no one else has. I really don't mind answering a few times a month, I was a noob once too. One of the most encouraging things about learning to brew is the help from people on HBT. You gotta pay it forward and graciously answer the questions even if someone could have searched and found it....if you don't want to, just ignore, don't say anything and move on.

This may not count, but make sure you trim off the triangle extrusion nipple on the bottom. That's what clogged on my blow off and caused a hop spray explosion all over my living room furniture !

Everyone just use your common sense /thread


Yes the yeast is still taking care of business in the late stages so you might as well just play it safe and let if ferment for longer than you think

KeyWestBrewing said:

I didn't feel like the OP was being pompous or a know it all. Sure the info isn't anything new and has been posted here many times. It's still not a big deal dude there's no need for the insults. Take that talk to the debate section.

I'll also point out the person that posted right before you found this thread reassuring. That alone makes the thread worth it.

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As a noob I have done extensive amounts of searching and reading on this forum. There are going to be topics that have been covered time and time again but as a noob I may not have thought of yet. So topics like this are helpful and spark thoughts that lead to more searching in the hopes of picking up golden nuggets of information.

kepo said:

As a noob I have done extensive amounts of searching and reading on this forum. There are going to be topics that have been covered time and time again but as a noob I may not have thought of yet. So topics like this are helpful and spark thoughts that lead to more searching in the hopes of picking up golden nuggets of information.

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That's the exact reason I gave my opinion. There's going to be a lot of stuff that gets repeated but HBT gets new members every day and has brewers at different stages in the hobby looking for all sorts of different information. Not everyone is used to being a part of a forum so their really trying when they come here for help. As brewers we have to help each other out, especially people just starting, even if that means answering the same question or providing the same info time and time again.

Not to mention that if we could not answer questions already answered somewhere in the 10 gazillion replies the forum would die.

I think it is good to answer some questions even though beat to death. It may be old hat to us but to a lot of people it is all new and confusing.

Not to mention just today there were 2 noob questions that I went and researched and learned something new myself.

I should rephrase and sorry for any misunderstanding... until you get used to your equipment, you will not know if airlock activity is an indicator of completion of fermentation. So no need to watch it as an indication of when to transfer or bottle.

WesleyBrewViking said:

I like looking at my airlocks for the soothing, hypnotic effect of the bubbles. It's very calming. Combine that with the aromatherapeutic aspect of fermentation (airlock sniffing) and it's like a home spa treatment for brewers.

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GD I love that smell! It's magical and I'm thinking of creating a fragrance for the on line vendors to sell. "O De Brew" I'm calling it.

Add me to the list of brewers who do look to airlock (or blowoff tube) activity as a sign of active fermentation.

I park my fermenter in a closet. No not my wifes closet no never again And forget get about it for a couple of weeks until I rack it. I do not worry if it finishes fast or anything. And that is why a pipeline is a wonderful thing.

Pappers_ said:

Add me to the list of brewers who do look to airlock (or blowoff tube) activity as a sign of active fermentation.

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I said that in the beginning! The whole point got lost somewhere, nevermind.

Airlocks will show you visibly when your beer is in it's most active stages.

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Pappers_ said:

Add me to the list of brewers who do look to airlock (or blowoff tube) activity as a sign of active fermentation.

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I think blow off tubes can safely be grouped in with "air lock activity."