Brewing beer in many ways is like being a new parent, especially when it comes to worrying over the bubbling of our fermenters. It’s hard not to take the visual signs of brewings as a definitive indication of what’s happening under the hood, but there’s more to the process than bubbles.
So, what should you do if your beer has stopped bubbling in your fermentation vessel? Bubbling is a good visual sign of healthy fermentation but it isn’t the best way to tell if your beer has finished fermenting. In order to determine if your beer is ready for the next stage in brewing, take a reading with a hydrometer or refractometer to check the change in its specific gravity.
I remember my first ever batch of beer was very energetic for the first day or so but then nothing. No bubbles, no visible activity, nothing. I panicked, but I needn’t have done as all the action was happening under the radar. In this article, I’m going to go into a lot of detail about what to do if you face a similar situation.
So let’s go through a few scenarios and you can follow the best course for your personal situation.
No visible sign of fermentation
Although very rare, let’s go over what to do if you have a beer which seems totally inactive and no fermentation seems to have started at all.
Well, as you probably know the way that we turn sweet wort full of those wonderful fermentable sugars into thirst-quenching beer is by using the labor of tiny yeast cells in the fermenter.
If fermentation hasn’t even started, then it’s probably because of one of two major problems. One, the wort doesn’t have the nutrients (sugar) in it for the yeast to get its teeth into and start converting into ethanol and CO2. Two, the yeast you have pitched your wort with is either inactive, not numerous enough or just plain dead.
For the first scenario, the best and only real course of action is to check the density of your wort and beer. By this I mean take a sample of your wort before you pitch it with yeast and also afterward.
Of course, this is easy to say with hindsight. What you need to look for is if your beer (after pitching) is similar in density to the target original gravity given in your recipe. If it is, then you have the right amount of sugar nutrients suspended in your beer for the yeast to feast on.
For scenario two, I go into a lot more detail on how to determine if your yeast is kaput or not in this article here. But some quick checks include fishing out the packaging for the yeast and checking the expiry date. Considering if you stored in properly in a refrigerator. Reviewing your brewing notes and checking the temperature you pitched it at. Determining if your fermentation vessel’s temperature is optimal for fermentation. Finally, did you use a yeast starter or not?
If everything seems within normal limits, then keep monitoring your beer’s density with daily specific gravity readings. This should give you an indication that the density is reducing as sugars are being converted into alcohol.
Fermentation seems to have stopped
If it was very obvious that your yeast began fermentation with a vengeance, then we can assume that we aren’t dealing with dead yeast cells from the beginning.
However, it is possible that they have become inactive because of several other factors since fermentation started. I have another article where I also discuss some of these issues to do with stuck fermentation which you can check out if the common issues below don’t apply to you.
Again, the only sure way to check for fermentation when you can’t actively seem it happening with your own two eyes is to monitor the change in your beer’s density over time.
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Common issues and fixes
Sometimes, the lack of bubbles can be due to very simple causes, often with equipment and outside factors.
If you saw bubbles in the early stages of fermentation when using a blow off tube (see my article for more details) but then none after you fitted your airlock, it could quite simply be due to a small air leak somewhere. If you are using a carboy, then there is probably only one area to worry about, a plastic fermenting vessel or bucket leaves more possible locations for a leak.
For this brew, the carbon dioxide is probably just finding an easier place to escape now that its production has lessened. Even with a leak, your blow off tube would have taken a lot of gas out of the fermenter and that’s why it was more visible. Try wrapping the top of your fermenter in kitchen plastic (cling film, saran wrap) to try and minimize the risk of bacterial infection and oxidation.
When you finish this batch, try filling your beer with a baking soda and water mixture and run a soapy sponge around the seals of your fermenter to find where the leak is coming from. It could be as simple as not pushing an airlock plugin properly or not screwing something down well enough.
Another thing that could easily affect the vigourousness of fermentation could be the temperature of the brewery and fermenting vessel.
My first brew was in the height of summer, which gets pretty hot where I live at the moment. Being a new brewer, I didn’t realize that not only was it hot outside, but the fermenter could be several degrees hotter due to the chemical reactions in fermentation.
So, make sure that you keep the temperature of your brewing room and fermenter within the suggested limits (normally below 69-71°F/21-22°C) by using a second-hand refrigerator, cold towels or even a cool ice bath when necessary.
On the other hand, make sure that your brewing space and fermenting beer isn’t too cold. This can make the yeast in your beer flocculate, fall out of suspension and become dormant. Again, this depends on your particular beer recipe but anything below about 50-55°F/10-13°C is going to have an adverse effect for most fermenting beer.
In this case, you may need to insulate your fermenting vessel from the ambient air in the brewery. Blankets, towels or even a sleeping bag are good low-tech ways to do this. Another avenue open to you is to purchase a heating pad for your fermenter to sit on which will maintain the right amount of heat.
Quick checklist for bubbleless fermentation
If the answer to any of the questions below is ‘no’ then fix that issue before panicking, if you answer ‘yes’ to all questions, then monitor the specific gravity of your beer for no change for another 2 days before getting worried!
- Is your fermenter airtight?
- Is the temperature of the room and fermenter correct?
- Did you pitch with viable and enough yeast?
- Are you keeping a record of the specific gravity?
- Is your beer still in the primary fermenter?
The collapse of the brown foam
Another visual sign that many new brewers may use, wrongly, as a sign that fermentation is finished is the foam which builds on top of the beer’s surface. This is known as krausen and is certainly a sign of fermentation, but when it naturally collapses back into the beer, it doesn’t always mean that things have stopped.
It could just be a sign that the production of carbon dioxide has slowed as your yeast community has become less active due to temperature, lack of nutrients or simply that fewer yeast cells survived to this stage of fermentation.
For more information about krausen and its impact on your beer, have a read of my article about this ‘curly’ foam here.
How long until your airlock should bubble?
As a general rule of thumb, whether you use dry yeast or a yeast starter, you shouldn’t expect to see immediate signs of fermentation. The first bubbles or belches from your beer will most likely start anywhere from 4 to 24 hours after you pitch the wort.
Of course, this really depends on how you introduce the yeast into the wort and on the number of nutrients and the ambient temperature of the liquid. Expect a lot of action in the first couple of days and then a slow reduction in the amount of carbon dioxide after 3- 7 days of pitching.
How often should fermenting beer bubble?
This is entirely dependent on each individual brew and there are so many factors at play that it would be impossible to give one blanket response. This being said, several bubbles a second in the first 24-72 hours of fermentation isn’t uncommon.
In later stages of fermentation, you may only get one or two bubbles a minute which is perfectly normal. Again, this depends on many different facts including how much headspace you have in your fermenter for the volume of beer you are fermenting.
The main thing to remember is that even if you get only a few bubbles a minute, don’t take this as a sure sign that fermentation has ended or even ended too soon. Always back up the visual signs with a scientific density reading. That is the only way to really find out what is going on in your fermenter.
Will beer continue to ferment in secondary?
Yes, it certainly will. However, secondary fermentation is fast falling out of fashion among the brewing community so this may not be a question that remains relevant for very long.
However, with common practices, you shouldn’t expect the same vigor in the fermentation which takes place in the secondary fermenter. There is a lot less active yeast left in the beer at this stage and therefore you won’t have as much activity in terms of bubbles in the airlock or on the surface. So, don’t panic if things see to have settled down somewhat at this stage.
Leaving a non-bubbling beer. Can you ferment beer too long?
I suppose the fear is that if you leave your beer longer as it seems not to be producing bubbles when you’ve been told it should, what is this going to do to your finished product?
Well, within reason, you cannot adversely affect your beer by allowing it to ferment for as long as it needs. The yeast in your beer is simply going to carry on converting those fermentable sugars for as long as they are available and it is able to do so. When yeast reaches its capacity or there is nothing left which it can use as a food source, it’s simply going to drop out of suspension as it flocculates with other cells and then sinks to the bottom of the container.
So, there is no real danger in leaving a beer to ferment for a couple of extra weeks as long as it’s not being exposed to the light or air. This way you aren’t going to run the risk of off-flavors before you get the fermented beer safely in a bottle or keg for carbonation. At this stage, the presence of higher levels of alcohol in the beer makes bacterial infection less likely, so at least that’s something less to worry about!
Zero bubbles equals zero need for an airlock, right?
If your beer isn’t even bubbling, is there much use using an airlock or should you just leave that bunghole open? It’s a fair question, but the answer is a resounding yes, you need that airlock (or something similar) even if bubbles aren’t flowing through it.
The job of an airlock or blowoff tube is to protect, for the most part, against oxidation of your beer which is going to leave it tasting pretty funky. By having a water barrier either in the airlock or in the blow off tube’s secondary container, you allow the escape of CO2 without the entry of O2.
So, make sure that you don’t lose your cool and chuck your airlock away for not doing it’s cool little job and showing you the work your yeast has been doing. It has a very important job, and even when nothing seems to be happening, it’s keeping your beer nice and safe from the outside world!