Trust Your Airlock

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AnOldUR

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If your fermentor doesn’t leak and you keep it at a constant temperature, airlock activity absolutely is a sign of fermentation. The term “off-gassing” is sometimes misused. If the temperature of finished beer goes up it will off-gas CO2 through the airlock. Also, thermal expansion will push gasses out of the airlock of finished or unfinished beer. If the temperature remains constant, the CO2 rich and neutral pressure environment in the head space of finished beer will allow it to hold onto the CO2 that is in suspension indefinitely. Under these controlled conditions, if you have airlock activity, you still have fermentation going on (it may be an infection, but still it’s still fermentation. :eek:) The reverse is also true. With no leaks or temperature changes a lack of airlock activity means your yeast is finished or never started to begin with.

Hydrometers are sometimes nothing more than an excuse for us noobs to play with our beer. You really only need three readings. One pre-boil to confirm your mash/lauter efficiency (so that you can make hop adjustments.) Another before fermentation, and the last before bottling to confirm attenuation. If you leave your beer in the primary for a few weeks at the proper temperature and you pitched health yeast in the correct amount into well oxygenated wort, your beer is finished if airlock activity has stopped for several days in a row after that time (run-on sentence, sorry.) Another hydrometer reading should not be necessary (edit: after this one if it determined that your beer was finished . . . but it might be if your beer hasn't fully attenuated.)

Yeah, we've had that stubborn saison, but . . . trust your airlock!


So science people, is this so wrong?
 
Yup, I have had the occasional leaky bucket or carboy cap but 99% of the time airlock activity matches the hydrometer.
 
so you are so pissed at me that what, you are going to start one of these threads for each of the things that I have written about???

Jesus man, it THOUGHT the discussion in the other thread was all in good spirit, even the jesting....I've always thought you were a great guy and have always respected you, AND thought that last discussion was in good sport.....I'm sorry if I hurt your feelings, dude.

But geez this is pretty transparent.....

You gonna start timing your bottle carbonations to see if 3 weeks at 70 degrees is wrong too???

Oy Veh.....
 
The conditionals you mention (completely sealed fermenter, zero temperature fluctuation) make your statements valid, Herm.

However, in practice, these conditions are extremely difficult to meet under most circumstances.
 
I'm sorry if I hurt your feelings
You flatter yourself. No feeling hurt, just the pursuit of accurate information for those with questions. This has been a thought that has come to mind every time the topic comes up. (And it does come up often.)
 
If your fermentor doesn’t leak and you keep it at a constant temperature, airlock activity absolutely is a sign of fermentation. The term “off-gassing” is sometimes misused. If the temperature of finished beer goes up it will off-gas CO2 through the airlock. Also, thermal expansion will push gasses out of the airlock of finished or unfinished beer. If the temperature remains constant, the CO2 rich and neutral pressure environment in the head space of finished beer will allow it to hold onto the CO2 that is in suspension indefinitely. Under these controlled conditions, if you have airlock activity, you still have fermentation going on (it may be an infection, but still it’s still fermentation. :eek:) The reverse is also true. With no leaks or temperature changes a lack of airlock activity means your yeast is finished or never started to begin with.

Hydrometers are sometimes nothing more than an excuse for us noobs to play with our beer. You really only need three readings. One pre-boil to confirm your mash/lauter efficiency (so that you can make hop adjustments.) Another before fermentation, and the last before bottling to confirm attenuation. If you leave your beer in the primary for a few weeks at the proper temperature and you pitched health yeast in the correct amount into well oxygenated wort, your beer is finished if airlock activity has stopped for several days in a row after that time (run-on sentence, sorry.) Another hydrometer reading should not be necessary.

Yeah, we've had that stubborn saison, but . . . trust your airlock!


So science people, is this so wrong?

I havn't seen a single bubble from my airlock (which would indicate "airlock activity") from my Oktoberfest primary in 5 days (and i've looked enough) and in those 5 days my beer has gone from a 1.026 (after 2 weeks) to a 1.020 SG (after 2 weeks, 5 days). If, for some reason, there has been activity and I have just missed it (unlucky) then I still feel comfortable about using my hydrometer as my gauge because I am not going to waste anymore time than I already have by staring at the airlock to try to catch a glimpse of the odd bubble (activity). Although I have not met your "few weeks" mark prior to taking a final reading this would seem to indicate that airlock activity or lack of activity does not necesarrily, by itself, indicate whether or not fermentation is taking place. I am not sure I understand why anyone would argue overuse of the proper tool for the job. Not all beers require a 'few weeks" to finish fermentation. Besides...playing with the beer is at least 50% of why I choose homebrewing as a hobby. The other half...yum...and...:drunk:.
 
However, in practice, these conditions are extremely difficult to meet under most circumstances.
I agree. Especially for beginners. But a carboy in a fermentation chamber will come pretty close most of the time. Even my basement temperatures are constant enough that I trust the airlock.

The truth is that a blanket statement either way can be misleading and out of place.
 
If the fermenter is completely sealed and the temperature is constant without fluctuation, the airlock will bubble during fermentation.

If it isn't, you have a leak somewhere.

You can indeed use the activity of the airlock as an indication of fermentation if you recognize that its accuracy is subject to outside variables like those listed above, and the only 100% accurate way to determine completion is using a tool like the hydrometer or refractometer. Excessive sampling does nothing.

You have to know the limitations.

By way of example: my Mild is constantly on tap at the house, and as such, I often have a batch 'in process'. I've brewed this recipe enough times using the same yeast or by introducing a single variable that I can tell from experience that two weeks from pitching and it is ready to go, on the button for calculated FG. If I'm experimenting with a new strain, out comes the hydrometer to log the ferment. I test my intuition from time to time using the hydrometer, but I can recognize completeness by visually inspecting the beer in the carboy. I don't use an airlock except in rare circumstances.
 
There can be fermentation without airlock activity in a perfectly sealed vessel. The co2 will no escape through the airlock until all the deadspace is filled. Hour many hours of fermentation is that before it's filled? So yes you can have fermentation before airlock activity. You cannot translate theory into practice. The hydrometer PROVES without a doubt something has happened. Airlock only proves a change in pressure. You can have airlock activity froma drastic temp change without any actual fermentation. So yes, this is so wrong.
 
One could also argue that just because fermentation has stopped, that does not mean that your fermentation is complete. There are so many variables that I would never simply trust my airlock to think "oh, it's done."

Often I don't check my FG using the hydrometer for the "drinking" beers, but that's because I had a high pitching rate, the proper temperature, plenty of agitation and let the beer sit for a long time.

New people that are waiting "7 days" to rack to secondary or even bottle should ensure that their beer is ready.

So while brewing is as much an art as it is a science, you cannot absolutely know where your beer is at without sampling it. You can practice brewing this way, you are simply not getting all the information you could otherwise.

Not to mention that fermentation completing does not necessarily mean the beer is ready. There is still flocculation, clearing, conditioning, etc.

Bottom line: Why not grab a sample, take a reading and a have a taste??? One of the most enjoyable experiences in homebrewing is tasting the beer at every stage and it literally takes 3 minutes.
 
I used to go by the airlock, until one time it didn't bubble and I very nearly pitched with an alternate yeast. I'm glad I didn't, because once I popped the lid to check with a hydro, I found the signs of fermentation. Somehow that lid didn't seal tight for the first time.

I very nearly pitched the wrong yeast as a backup (only yeast I had at the time). Now that I have more experience I know to check FG with the hydro, and for more than just to see if it's fermenting. It can tell me how much it fermented, and if it should be done (very closely)

I guess for some, the airlock is good enough. Not for me. Well, maybe in a carboy, but I mostly ferment in a bucket, where the chances of having a leak are much higher.
 
The co2 will no escape through the airlock until all the deadspace is filled.

This is a factor that I didn't consider! Goodonya for noting it. :)

I'd have to think that an adequate pitch of yeast into a well-oxygenated wort will fill a headspace quite quickly, probably within hours. If one were fermenting a 3 gallon batch in a 6.5 gallon carboy, this would be more of a factor.
 
I thought this was the science forum?

Nothing here but anecdotal evidence.

Where is the science?
 
I thought this was the science forum?

Nothing here but anecdotal evidence.

Where is the science?

Observation is a "scientific" method. Particularly when combined with the application of some form of established metric (like that associated with a hydrometer).
 
This is a factor that I didn't consider! Goodonya for noting it.

So what, you suck all the air out of your carboy after you put the lid on? :cross:

From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.

And I'm not saying that airlock activity is the end all choice of determining your beers condition, but it is the primary tool. A very low tech, but potentially accurate tool.
 
So what, you suck all the air out of your carboy after you put the lid on? :cross:

From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.
The head space only has to be pressurized enough to push the hat on the airlock out, but the liquid does have to become saturated with CO2 before it starts to release it. This will depend on the temp of the solution, so the warmer it is the less saturation will occur before it releases gas. This is a pretty minimal amount and it doesn't take long for the saturation to occur, but there is CO2 being produced before it starts pushing out of the airlock.
 
So what, you suck all the air out of your carboy after you put the lid on? From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.

That's what I was going to say. Somehow I doubt that people have a vacuum in their headspace prior to fermentation.

And I'm not saying that airlock activity is the end all choice of determining your beers condition, but it is the primary tool. A very low tech, but potentially accurate tool.

IMHO, it's a crude visual indicator that helps determine when to take a hydrometer reading. I use glass and BB carboys, so I usually rely on watching the wort more than I do airlock activity. I usually only take 2 or 3 readings. I have a refractometer, so I don't need to take anything prior to it going into the fermenter. I take my first hydro reading just prior to pitching; my second one is taken when I feel the bulk of fermentation has subsided (when the sugars are consumed, and it's transitioning into the conditioning stage). This is done to make sure I hit my target FG...if it hasn't, then I will either heat it up and stir, or I'll pitch onto another cake. I might also take one just before I rack to the keg, to make sure it's where I want it to be.

But just like Revvy's blanket statement that your airlock is unreliable, this blanket statement that it IS, is not helpful.
 
Call me a nerd, but I'll stick to Hydrometer readings.

The parameters that qualify your statement are loose at best and I dont think can be guaranteed with typical homebrewing equipment.
 
So what, you suck all the air out of your carboy after you put the lid on?

From the very start of fermentation CO2 will be displacing the existing air and pushing it out the airlock. If you don't have a leak you have bubbles right from the start.

This is why I don't do science. :drunk:

I'll stick with my artsy fartsy humanities stuff, thanks! :rockin:
 
But just like Revvy's blanket statement that your airlock is unreliable, this blanket statement that it IS, is not helpful.
You are right and in post# 7 of this thread I acknowledged that, but it does bear repeating.

My OP wasn't a blanket statement. It was a well-defined conditional statement.
 
Changes in atmospheric pressure can affect the amount of airlock activity. It wouldn't make much difference during active fermentation, but it could mask things as fermentation slows, causing you to think it's done, when it's really just slowed down. conversly, it could lead you to believe fermentation has re-started.
 
. . . but the liquid does have to become saturated with CO2 before it starts to release it.
Good point. Didn't think of that. But lets not let anyone think that this amount would ever be enough to consider your beer finished.

No bubbles in your airlock should always be a reason for concern. It might just be a leak, and ignoring it may still produce good beer, but if I don't see bubbles, I want to know why.

I leave my beer in the primary well after fermentation has stopped. In the early stages, out-gassing will prevent outside air from getting into a leak, but after fermentation has stopped thermal contraction will suck air in. In my damp basement, I'd hate to have some moldy spore dropping by during that sucking process.


(he he he . . . I said sucking process)
 
really i dont know what all the fuss is about i almost never use my Hydrometer.
Yeah i know crazy right!
I just dont have any use for it, unless i am making some super hi-gravity beer or if i am making a mead wine or something odd i have never done before.
most of the beer i make i have made many times in the past and have my set recipts and logs ect at this point i just know where its at.

I can tell by look ,taste and flow if my mash was on target , and i really dont care what the 100% correct alcohol% is anyway. i ferment in glass and have never had a leaky stopper.

airlock action, plus yeast clean up time is all i need for most of the ales i make, i almost never use a secondery anymore , and just wate till flocculation is compleat then wate a few more days and then rack to keg and carb, that way the ferment gets opened just once at kegging time and my hydrometer stays nice and safe on a shelf in its case where it belongs :)
 
Hydrometers are sometimes nothing more than an excuse for us noobs to play with our beer. You really only need three readings. One pre-boil to confirm your mash/lauter efficiency (so that you can make hop adjustments.) Another before fermentation, and the last before bottling to confirm attenuation. If you leave your beer in the primary for a few weeks at the proper temperature and you pitched health yeast in the correct amount into well oxygenated wort, your beer is finished if airlock activity has stopped for several days in a row after that time (run-on sentence, sorry.) Another hydrometer reading should not be necessary.

-1

This is just silly and lazy. Have I ever racked to a secondary without checking the gravity? Sure. Doesn't mean it's not lazy. There are times when I wind up leaving something in a primary for 2 weeks because I don't have time to address it. To me, as long as I've seen the krausen drop, then I'm generally confident that it's good to go.

That doesn't mean that I don't think I that the general consensus that you check your gravity after that set number of days (5, 7 or 10, or whenever) to check if fermentation is done is just an excuse to play with my beer and my beer 'toys'. The hydrometer readings let me calculate my ~ABV%. It gives me the confidence to know that the conditions in my brew closet and my brew process were on par with every other batch I've done. Why should I wait until bottling day, up to 3 or 4 weeks after I move it from primary to secondary to check my gravity? What if I'm using harvested yeast and I don't realize it's pooping out until I've made another batch? I can know in 7-10 days, rather than waiting 30-45 days.

Is this really as traumatic as you or I are making it sound? No, but to say that I'm looking for an excuse to take readings (potentially infecting my beer) is just silly. I'm doing it for a reason. To make the best beer I possibly can and to learn about my process and make it better.

/edit: The original topic is apparently an "attack" (whether friendly or full of malice) on Revvy's often quoted gospel (see what I did there?) that the air lock should not be used to determine if fermentation is complete. I agree with Revvy's side of the "debate", but I don't think it needs to be as tragic as it sounds.
 
really i dont know what all the fuss is about i almost never use my Hydrometer.
Yeah i know crazy right!
I just dont have any use for it, unless i am making some super hi-gravity beer or if i am making a mead wine or something odd i have never done before.
most of the beer i make i have made many times in the past and have my set recipts and logs ect at this point i just know where its at.

I can tell by look ,taste and flow if my mash was on target , and i really dont care what the 100% correct alcohol% is anyway. i ferment in glass and have never had a leaky stopper.

airlock action, plus yeast clean up time is all i need for most of the ales i make, i almost never use a secondery anymore , and just wate till flocculation is compleat then wate a few more days and then rack to keg and carb, that way the ferment gets opened just once at kegging time and my hydrometer stays nice and safe on a shelf in its case where it belongs :)

Does this mean that you believe that there is no chance, at all, that yeast will stop eating (and flocculate) before all fermentable sugars are consumed? I realize that you didn't say as much but it leads to a question for clarification. If indeed you believe it so, that is a brave assumption that could leed to some beers that could potentially be on the sweeter side to some liking. Perhaps you don't mind if your beers are on the sweet-side. I happen to care, so I will continue to utilize hydrometer readings as my main indicator of completed (or near enough completed to my liking) fermentation.
 
i almost never use my Hydrometer.

I'll take an OG reading, but other than that, I don't use it much anymore either. As you say, we brew these beers over and over again. You just get a feel for it after so many times.

However, I do think new brewers should use it until they reach a more experienced & comfortable place in their brewing...
 
You just get a feel for it after so many times.

You get a "feel" for completeness of fermentation? A rare gift indeed. :confused:

Perhaps I am too new to the process to understand that way of thinking. I mean, I get a "feel" for when I should be taking a hydrometer reading but i don't think we are talking about the same thing here.
 
You get a "feel" for completeness of fermentation? A rare gift indeed. :confused:

Perhaps I am too new to the process to understand that way of thinking. I mean, I get a "feel" for when I should be taking a hydrometer reading but i don't think we are talking about the same thing here.

He's The Yeast Whisperer(tm).
 
You get a "feel" for completeness of fermentation? A rare gift indeed. :confused:

Perhaps I am too new to the process to understand that way of thinking.

Perhaps so, but yes, you can get a feel for it. After 400+ batches of beer, if I haven't learned something, that would make me pretty dumb...and I may be a little dumb, but I'm not plumb dumb.
 
You get a "feel" for completeness of fermentation? A rare gift indeed.

See my comments here:

By way of example: my Mild is constantly on tap at the house, and as such, I often have a batch 'in process'. I've brewed this recipe enough times using the same yeast or by introducing a single variable that I can tell from experience that two weeks from pitching and it is ready to go, on the button for calculated FG. If I'm experimenting with a new strain, out comes the hydrometer to log the ferment. I test my intuition from time to time using the hydrometer, but I can recognize completeness by visually inspecting the beer in the carboy. I don't use an airlock except in rare circumstances.

Now, before everyone gets their knickers in a twist, please note that this is a recipe that I've brewed countless times since I developed it, and it is a staple coming out of my brewery. I know what to expect with the ferment under my normal fermentation schedule/temperature, etc. I have that familiarity with the yeast, the recipe, the ferment conditions. To keep myself honest, I break out the hydrometer occasionally to verify my intuition.

I'm a firm believer in using the tools at my disposal in making the best beer that I can, but excessive hydrometer use isn't helping a thing, ya dig?
 
I think the 'don't trust an airlock' sentiment is way, way overstated. I have always gone by the airlock. I do take a hydro sample...as I'm racking. But I've never needed to take a gravity sample while it's still in the fermenter...ever. I've taken a grand total of one hydro sample from a fementer and that was shortly after I joined here (lots of others were doing it so I tried it and wondered; "WTF am I doing this for? I KNOW it's done.").

I can understand telling noobs to not go by the airlock but once you've brewed a few batches you learn how it all works. Then you can choose whether or not to use it.

If I can tell if how a fermentation is coming along just by looking at it (not just the airlock...the krausen, turbidity, clarity, etc.) then so can just about anybody. If not, then perhaps it's a case where a person becomes oblivious to the most obvious things simply because they have a tool for telling them. Like if a cook always used a meat thermometer for telling if steaks are done...that cook may not be able to tell just by pressing on it with their finger (and lol @ that cook!).
 
I think one point we should drive home here is that this is not good recommendation for newcomers or specialty beers.

Using the airlock as an indicator will work fine for tried and tested batches, high pitching rates, smaller beers, optimal conditions, etc. but as soon as someone makes a belgian triple, a large weizenbock, or simply is making a beer with "old" yeast, it changes everything.

Telling someone that using the airlock is an acceptable method of fermentation indication is simply bad advice. Yes, it can be done, but no, it WILL NOT tell you where your beer is at.

YOU might know it's done because you've "done it dozens of times" or YOU have optimal conditions, but that doesn't mean it will work every time for every person for every beer.

There is only one sure way to see where your beer is at. Take a sample, take a reading and take a taste.
 
Telling someone that using the airlock is an acceptable method of fermentation indication is simply bad advice.
You are correct, but telling some that the airlock is a useless tool is also bad advice. From the beginning it's been said here that they both have their place in brewing. One compliments the other. And neither should be ignored.
 
Sure, but the airlock was made for the sole purpose allowing gas to leave the fermentation container. It works great for that purpose. IMO, it should never be used as an indicator of fermentation.

If you know that fermentation is complete because your airlock has stopped, you are taking other things into consideration. You know it has been long enough, you know you pitched enough yeast, you know the temperature was correct, you know possibly because of your experience and the original gravity, etc.

Sure, you can judge your fermentation based on your airlock activity, but it will never be a proper alternative to taking a sample.
 
Is this really as traumatic as you or I are making it sound? No, but to say that I'm looking for an excuse to take readings (potentially infecting my beer) is just silly.
No, it’s not traumatic, just an observation. What’s silly is denying the value of a very basic tool. The hydrometer has a place in the brewing process. The quote you referenced states that. But there is in no real excuse to take a reading when it’s not necessary. If you don’t see airlock activity for 5 days, sure, take a reading. Sure, you want to check a wheat beer before a IIPA. But if your conditions are stable for that IIPA and you still have bubbles after two weeks, it’s not done. Put the hydrometer away and show some patience!


What if I'm using harvested yeast and I don't realize it's pooping out until I've made another batch? I can know in 7-10 days, rather than waiting 30-45 days.
So, you pitched this harvested yeast without making a starter to verify it being viable, there was no airlock activity and no krausen in your fermenter and it took you 7-10 days to figure that there was something wrong by taking a hydrometer reading? Now who's being silly? :cross:


I agree with Revvy's side of the "debate", but I don't think it needs to be as tragic as it sounds.
Not saying it’s tragic, just trying to show that Revvy’s word isn’t always gospel.
 
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