Airlock Activity as a Gauge of Fermentation

[wolf08gang]

Some say that you shouldn't gauge fermentation activity by how fast your airlock is bubbling.

My argument to the contrary:

I absolutely use the airlock as a gauge. Every time I brew, I will check the airlocks the next day for activity. If they are happily bubbling away, I know that I have an active fermentation. If they are not bubbling, I know that one of the following must be true:

1) The fermentor is not sealed up properly thus allowing the co2 to escape somewhere other than through the airlock.

2) The beer is not actively fermenting.

I can then use this information to decide upon a course of action.

Then, when I want to check if the beer is done fermenting, I will check the airlocks again. If I still see airlock activity I will leave it alone to do it's thing a while longer.

The reason I can use the airlock as a gauge of fermentation activity is that it is a direct cause and effect relationship. Yeast consume sugars and excrete alcohol and co2. This process is called fermentation. The co2 produced causes the pressure in the fermentor to exceed that of the air surrounding it. That pressure is relieved through the airlock causing bubbles in the fluid. I can observe those bubbles and recognize that fermentation is taking place.

To illustrate: Exhaust fumes are a direct product of the combustion of gasoline in the engine of a car. If I observe exhaust escaping the tailpipe of a car, I can reasonably assume that the engine is running. I don't have to jam my fingers in the serpentine belt to be certain.

A couple of caveats for new brewers:


1. Sometimes if you allow the fermenter to warm slightly for any reason, the bubbling will resume. This can be alarming if you thought the fermentation was complete. What's happening is that the air in the head space is expanding and/or some of the dissolved CO2 can come out of solution and escape through the air lock. It may take awhile for this activity to subside, but it's nothing to worry about.

2. The same thing can happen when you rack to the secondary. The turbulence created when racking can trigger release of some of the dissolved CO2 and it will escape through the air lock. Again, nothing to be alarmed about at all. It doesn't mean that the fermentation was not completed.


Discuss...

 

[addis29]

What exactly are you wanting to discuss? Sounds like you covered it.

 

[Cliff897]

I think that when people make that comment it is in the context of the secondary ferment when the yeasts are doing house keeping cleaning up all the left over bad flavors.

While you may see bubbling in the secondary, it is not always that you do, and it is not an indication of yeast inactivity when there are no bubbles.

There is a hell of a lot going on in the conditioning phase.

 

[jgilbreth]

I think the big reason a lot of people preach against using the airlock as an indication is that if you do not have an airtight seal, it can give you a false reading. I use plastic buckets for fermentation with seals, so rarely have an air leak.

In general I agree with you, with the airlocks I use, if the cap piece is elevated, there is positive pressure in the fermentation vessel, and therefore active fermentation. When it drops, it is almost done. I push on the lid a little bit too, and if the cap rises, I still have an airtight seal.

Nothing replaces a hydromenter (or other device) for gravity readings, but the general start and stop of fermentations can me metered by the airlock activity, in my opinion.

 

[Catt22]

I use my air lock as a gage of the fermentation activity. Is this a sin?

 

[jtlawlor]

I understand your point - but ... your post isn't really in contradiction to Revvy or anyone else. Most people watch their airlock...

When Revvy and anyone else states that you shouldn't use the Airlock as a gauge for fermentation - it is to quell noobie fears that they have messed up - or that they should now bottle because the airlock stopped after 3 days, and should use their hydrometer instead... or a bunch of other fears... instead of Relax, Don't Worry....

 

[ChshreCat]

The problems with using your airlock to gauge fermentation is that it can lie to you. Your airlock can bubble for 5 days and then stop. That would mean your beer is done fermenting but it could also be stuck and sitting at 1.025. So you bottle, fermentation starts back up again and you get overcarbed beer and/or bottle bombs.

You could also see bubbles when nothing at all is happening due to changes in temperature or due to CO2 offgassing.

Nothing wrong with checking your airlock for activity and a good stream of bubbles is a FAIR indicator that fermentation is happening, but you should still use your hydrometer as the final judge of what's happening in there.

 

[Catt22]

"Nothing wrong with checking your airlock for activity and a good stream of bubbles is a FAIR indicator that fermentation is happening, but you should still use your hydrometer as the final judge of what's happening in there."

IMO, a good stream of bubbles is more than a FAIR indicator, it's an EXCELLENT indication that fermentation is well under way. How could it be otherwise?

 

[GilaMinumBeer]

May Revvy have mercy on your soul.

 

[wolf08gang]

You could also see bubbles when nothing at all is happening due to changes in temperature or due to CO2 offgassing.

I covered that in the OP.

I'm not suggesting we all throw out our hydrometers. They are the most accurate measure of fermentation.

What I am suggesting is that telling newbs that you can't judge fermentation by airlock activity is misleading.

If I go downstairs and check my airlocks to see that they are still bubbling away steadily, I'm certainly not going to waste the effort, and risk contamination by opening the fermentor up and taking a sample. I'll wait a couple more days until the airlock activity has stopped or slowed considerably, then take a reading.

I can make this decision because I can perceive by the airlock activity that the beer is still fermenting. Thus, I use the airlock as a gauge of fermentation.

 

[wildwest450]

This worthless thread needs to be moved to the debate forum.

 

[wolf08gang]

This worthless thread needs to be moved to the debate forum.

Thank you for your observation. I thought this forum was for discussing subjects related to equipment and sanitation.

 

[Catt22]

brb...got to check my air locks

 

[Rhoobarb]

This worthless thread needs to be moved to the debate forum.

And this worthless post?...

I've been brewing for thirteen years and always used the airlock to judge. As was stated:

1) The fermentor is not sealed up properly thus allowing the co2 to escape somewhere other than through the airlock.

2) The beer is not actively fermenting.

That's it - end of story. Sure I use a hydrometer, but I don't bother with it until after I've counted bubbles every 60 secs. or longer. I'm not about to waste time or beer taking gravity readings every second or third day. Jesus!

 

[springer]

This worthless thread needs to be moved to the debate forum.

No it doesn't ...



In reality a seasoned brewer will use all the tools available to him to judge fermentation while yes the air lock if bubbling would be a good indication of fermentation one that isn't bubbling does not mean no fermentation is going on. I think the Don't trust the air lock is mostly directed at the NooBs who panic if they see no activity..

 

[Catt22]

The reason I don't like to take frequent and repeated gravity readings is that when you draw the sample you are introducing oxygen. Sure, you could do the purge thing with some CO2 to help mitigate the potential for oxidation problems, but that's more of a PIA than I want to deal with. I prefer to wait until there is no air lock activity and/or at least two weeks before I do anything at all for most of my beers. Sometimes longer for lagers or really big beers. I then typically rack to a secondary and take a hygrometer reading at that time to get the F.G. I don't dump that sample right away. Instead, I let it sit for a few days at room temp to see if it drops any. It only very rarely does so. I can also get an approximation of the SRM as it drops clear.

 

[Desert_Sky]

screw hydrometers. Airlock activity works just fine to gauge fermentation status. Especially if you ferment in a conical and cant see inside your fermenter. To hell with wasting a sample when you know where its going to be anyway.

Use a hydrometer when you start off or you are professionally brewing. Other than that let it go. Hydrometers only make you worry

 

[bob1852]

IBTR!!!!!

(in before the Revvy)

 

[Catt22]

ibtr!!!!!

(in before the revvy) :d

:d:d:......

 

[Laughing_Gnome_Invisible]

I only use a hydro these days if I am formulating a recipe.

For my regular house ales I know by experience when to move the beer, not simply by airlock activity. It's just experience on how well the temps were kept, how it looks, how it tastes......

I'm in both camps on this one. I've never bottled too early even when not using the hydro, but when I need it to define a recipe or check my efficiency I will use it.

I guess I'm somewhere between artist and scientist on my hobby.

 

[Catt22]

:d:d:......

........:d:d

 

[bob1852]

........:d:d

Third time's a charm!

 

[Boerderij_Kabouter]

IF the fermenter is properly sealed the airlock is a great indicator. For example, I know reasonably well that when my airlock bubbles at about 4 burps per minute that I have fermented about 2/3-3/4 of the fermentables and it is time to rack to a secondary fermenter should I so choose. I will use a hydro to double check, but the air lock is a great indicator and a tool that should be used.

 

[bob1852]

IF the fermenter is properly sealed the airlock is a great indicator. For example, I know reasonably well that when my airlock bubbles at about 4 burps per minute that I have fermented about 2/3-3/4 of the fermentables and it is time to rack to a secondary fermenter should I so choose. I will use a hydro to double check, but the air lock is a great indicator and a tool that should be used.

you guys are going to give Revvy a heart attack!!!!

- airlocks as indicators
- racking to secondary before fermentation is complete

 

[Laughing_Gnome_Invisible]

you guys are going to give Revvy a heart attack!!!!

- airlocks as indicators
- racking to secondary before fermentation is complete

I'll pre-empt that heart attack by saying that we DO understand that there are variables! Bad seal, wrong temps etc.......Should we break out the magic electric paddles?

 

[ArtVandelay]

Airlocks can be a good indicator of fermenation and you can get a general idea what is going on in there (has it started, has it stopped, etc?). However, a hydrometer will always tell you for sure if fermenation has started or stopped. There is much more risk in someone judging whether fermentation stopped if they are just basing it on airlock activity.

So I don't think there really is anything to argue about. Airlocks can indicate fermentation but shouldn't be relied upon.

 

[Cliff897]

Nope~!!

You need an HP quadrapole mass spectrometer and a HPLC column chromatography rig.
If you don't have that most basic of equipment you simply can't know what's going on

 

[MrShake]

airlocks can also indicate temperature changes and infections.....

Why are you checking your beer after 3 days anyway? Wort goes in fermenter and I don't look at it for at least 2 weeks.

The airlock serves a single purpose, to prevent stuff from falling into your beer. That is its only purpose.

 

[Laughing_Gnome_Invisible]

airlocks can also indicate temperature changes and infections.....

Why are you checking your beer after 3 days anyway? Wort goes in fermenter and I don't look at it for at least 2 weeks.

The airlock serves a single purpose, to prevent stuff from falling into your beer. That is its only purpose.

That is the primary purpose, yes.

However, if someone stops screaming, it is also a fair indication that they are no longer being beaten up. It is up to you, the police, to investigate the situation. As the Police officer you can either look at the situation with your years of experience and determine if the beating is over, or you can take a hydro reading of the victim..........OK, yes, I am just being facetious.

 

[malkore]

I use mine to gauge fermentation has started...by sniffing it. If it smells like its fermenting, I could care less if its gurgling the airlock or leaking out the lid that didn't seal well.

 

[Desert_Sky]

you guys are going to give Revvy a heart attack!!!!

- airlocks as indicators

Dude, brew a couple hundred times and use the airlock as your guide and you'll see. The only time I pull out the hydrometer is when I would brew on a new rig or change configuration in sparge or my MT.

When you know your water profile, grain characteristics, ph, pitching and O2 rates...well you bet your ass you can use airlock as a guide. I use time since pitching mostly, but at a glance I know exactly where I am by what the airlock is doing or not doing.

 

[wildwest450]

and O2 rates

How do you figure this?

 

[bob1852]

Dude, brew a couple hundred times and use the airlock as your guide and you'll see. The only time I pull out the hydrometer is when I would brew on a new rig or change configuration in sparge or my MT.

When you know your water profile, grain characteristics, ph, pitching and O2 rates...well you bet your ass you can use airlock as a guide. I use time since pitching mostly, but at a glance I know exactly where I am by what the airlock is doing or not doing.

my = sarcasm.....

 

[Catt22]

I picked up on the sarcasm right away, but the comment is still valid. If not a heart attack, at least a bad case of hemorrhoids