Fermentation for an IPA still going strong after 20 days?

[DrKennethNoisewater]

A little background:

I'm brewing a DFH 90-minute / Zombie Dust hybrid IPA with all grain. 5 gallon batch.

The recipe called for 10 days in primary and 10 in secondary. Then proceed with bottling as normal.

My question is this: it's the 20th day and I'm still getting bubbling in my airlock about once every forty seconds. Is it possible that this thing is nowhere near finished fermenting or is that still normal this far into the process?

The only thing I did different than my first two batches (also IPA's) was pitch two smack-packs of yeast this time instead of just one. I also dry-hopped an additional ounce of Citra two days ago.

Could this still-active fermentation have something to do with the extra yeast? Did my late hop addition stir things up again?

Any help is appreciated!

 

[plankbr]

Air lock activity is no measure for fermentation. Have you reached your final gravity? If so, let it sit for a day or 2 more, take another FG. If they are the same, it's safe to bottle.

 

[dickproenneke]

Have you taken a gravity reading? If not, then how do you know that your beer is still fermenting? The airlock isn't an indicator of fermentation, its only a vent for CO2 to escape. Maybe the bubbles that you are seeing is merely gas coming out of solution. My suggestion would be to take a gravity reading today and then another in two more days. If it hasn't changed then you are good to bottle.

Edit: the airlock isn't *always* an indicator of fermentation

 

[twistr25]

If you added the Citra only two days ago, that will disturb the liquid and cause CO2 to be off-gassed. Have you moved to secondary yet or this is happening in secondary?

 

[ten80]

Lets think of this logically. If:

fermentation -> CO2

and

CO2 -> airlock movement

then it stands that

fermentation -> airlock movement

It is not accurate to say "the airlock isn't an indicator of fermentation," because by definition, fermentation produces CO2, and the you cannot have substantial fermentation WITHOUT generating a positive gas pressure in the fermenter, which in turn causes airlock movement (unless your fermenter bung or lid leaks.

If the airlock was not an indicator of fermentation, then one could not explain the vigorous airlock movement that occurs during the peak of a fermentation, and the comparatively lower airlock movement rate before and after the peak.

However, I do agree that taking an FG is the best measure of fermentation progress as you are directly measuring the fermentation's progress (sugar/alcohol content) rather than making a subjective observation of airlock movement.

In general if an airlock continues to move after fermentation should be completed, it may be indicative of two things:
1. gas coming out of solution due to ambient temperature increase, resulting in decreasing gas solubility in the warming beer (as dickproenneke suggested)
2. wild yeast or bacterial infection producing CO2, H2S, or CH4 be fermenting beer to organic acids or fermenting dead yeast itself (the latter smells like a dying carcass)

In your case, it is possible that tossing in the hops either
1. added trace amounts of oxygen to the beer and head space, stimulating yeast activity
2. added wild bacteria and/or yeast that resumed fermentaton
3. disturbed the beer and/or created nucleation sites for CO2 bubbles, resulting in release of CO2. Beer in a fermenter is super-saturated with CO2 as a result of fermentation and it takes very little to cause CO2 to release

but it is possible that your fermentation was nutrient limited to begin with and as a result, the fermentation is going slower and slower as your final gravity is approached. The only way to tell if it is still fermenting is to take a gravity reading, however do note that SG readings can continue to drop as a result of fermentation or infection, both of which consume sugars from the wort.

 

[jesserizzo]

fermentation -> CO2

and

CO2 -> airlock movement

Except that it doesn't if your fermentor leaks.

fermentation -> airlock movement

Even if both the above premises were true, and you had proved that fermentation -> airlock movement, than it still doesn't mean that airlock movement -> fermentation

I do agree that others' assertion that "airlock movement isn't an indicator of fermentation" is false. It should probably be stated "airlock movement isn't always an indicator of fermentation".


Sorry to nitpick. Cheers.

 

[Clonefan94]

I do agree that others' assertion that "airlock movement isn't an indicator of fermentation" is false. It should probably be stated "airlock movement isn't always an indicator of fermentation".


Sorry to nitpick. Cheers.

I like this a lot better than "The airlock isn't an indicator of fermentation" It may not be, but it still doesn't tell the whole story. I have always seen airlock activity when I ferment. And to the OP, I've seen it after I ferment as well, for off gassing, pressure changes etc. But, if I pitched yeast and 3 days later still saw no activity in the airlock (I ferment in buckets), I would at least take a look to see if anything has started going on.

And I think this is a good thing for the OP. There are a lot of reasons why your airlock could be bubbling, you might want to take a look and check gravity, to see what's going on. I'm not saying it's impossible by any stretch, but it would definitely be an oddity if it were still fermenting normally this many days later.

 

[DrKennethNoisewater]

Ok.....a response to a few of your responses:

Yeah, it's in the secondary.

I have not taken a final gravity reading yet. I'll do so and then take another in two days to see if they match.

I'm new to this thing....bear with me! Only my third batch.

Thanks for the feedback.

 

[ten80]

Except that it doesn't if your fermentor leaks.

......

Sorry to nitpick. Cheers.

I said the very same thing, so you are nitpicking unnecessarily

To quote myself:

"(unless your fermenter bung or lid leaks. "

I did forget a parenthesis though.

 

[twistr25]

Ok.....a response to a few of your responses:

Yeah, it's in the secondary.

I have not taken a final gravity reading yet. I'll do so and then take another in two days to see if they match.

I'm new to this thing....bear with me! Only my third batch.

Thanks for the feedback.

Despite what your recipe says, you should make sure you are at or very close to final gravity before you move to secondary. If you take it off the yeast cake before it reaches FG, you could get a stuck fermentation and you'll finish high/sweeter. 95% of the time, you should hit a stable gravity in 10 days, but better safe than sorry.

So, considering the fact that it is now in secondary, not likely any active fermentation going on, but off-gassing from moving the beer and adding the dry hops that has disturbed the CO2 in solution.

 

[masonsjax]

Temperature fluctuations, co2 coming out of solution, disturbing trapped air in the trub, etc. can all cause airlock activity. If you want to be sure, use a hydrometer.

 

[WileECoyote]

Ok.....a response to a few of your responses:

Yeah, it's in the secondary.

I have not taken a final gravity reading yet. I'll do so and then take another in two days to see if they match.

I'm new to this thing....bear with me! Only my third batch.

Thanks for the feedback.

Your doing just fine, keep asking questions, and congrats on brewing your 3rd batch.

Brewing is one of those things that, you will always learn something new no matter how long or many batches you brew.

Like others have said, use the Hydrometer to determine if your brew is finished.

Cheers