Chocolate stout started bubbling in secondary

Brewed my second batch of chocolate stout last month. Starting gravity was 1.056. Left it in primary for about 17 days, krausen all re-absorbed, but couldn't check gravity (hydrometer broke, didn't replace it in time). Racked to secondary, where it has been for about 2 weeks (I am going to give it another 3 before I will bottle it). Just went down to the basement, and I noticed that there is slow but regular bubbling in the airlock, and foamy bubbles on the top of the brew. Secondary is a Better Bottle, and I am using an S type airlock (I use a 3 piece on the primary). It's been sitting at a pretty constant 68 degrees. Should I be worried that it somehow got contaminated?

I doubt it got contaminated, assuming you sanitized all equipment. I would check the gravity before you bottle to make sure it's done.

Checked gravity last night - 1.025. Terminal gravity should be about 1.017, so clearly it isn't done (and I'm not bottling for several more weeks). Does it seem odd that it's still fermenting after four weeks?

Yes....Especially if you racked it too soon, or you had a slow or stuck ferementation. Or there was a change in temp, or even the fermenter got nudged and the yeast woke up. That's why it's a good idea to replace our broken hydrometers asap, or have two, so you don't have speculation, or move things too soon. I know it may not seem like an important tool, especially if it gets broken, and you can still make beer without it, but if you had it, you may not have moved it early, and you may not have had this happen.

Revvy -

All good observations by you, as always. This was actually the first time I failed to take my readings, and it won't happen again. In fact, the temperature in my area (NYC) has gone up the last few days, I think the temp of the carboy has gone up a degree or two, and I really noticed this activity after I replaced the rubber stopper with a bung (which in turn had to be pushed farther down into the mouth of the bottle), and I also moved the bottle slightly at the time. In other words, a number of things might have woken up the yeast. But, things being as they are, here are my remaining questions:

1) For future reference, if I'm not absolutely sure fermentation is done in primary (but assuming krausen absorbed, and activity calm), is there any harm in racking to secondary? I know bottling at that point would risk creating WBDs (weapons of basement destruction), but won't the fermentation just continue in the secondary?

2) As long as I give this current batch plenty of time to finish in the secondary before I bottle it (which I will check with hydrometer - scout's honor!), is there any cause for concern (such as contamination)?

3) Any relevance to the possibility that this is a very slow fermentation or a revived stuck fermentation that this stout has 1/2 lb of cocoa powder in it (added during boil) or (used for the first time to increase fullness) that I also added 1/2 lb of maltodextrine during boil?

rwberne said:

and I really noticed this activity after I replaced the rubber stopper with a bung (which in turn had to be pushed farther down into the mouth of the bottle), and I also moved the bottle slightly at the time.

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I think this has more relevence that anything else, and I don't think necessarily that the yeast started working again, though it could with the temp swing....I think now, your airlock started bubbling because you opened it up closed it back up. And now it is off gassing the co2 that had built up and then sat undisturbed since you pitched your yeast, or racked it, or did whatever else you did awhile ago. You might have released some trapped co2 from the tube.

Often an airlock will bubble if the fermenter has been disturbed in some way, like a change in temperature, change in atmospheric pressure, the cat brushing against it, or opening it up to take a hydro reading.

The co2 has sat in stasis for a period of time, then it was disturbed so it is not longer at equilibrium with everything else now. And therefore it is blipping in your airlock

That's why I tell folks over and over that airlock bubbling and fermentation are not the same thing.Brewers have to separate that from their mindset. Airlock bubbling can be a sign of fermentation, but not a good one, because the airlock will often blip or not blip for various other reasons...so it is a tenuous connection at best.

And that's why really the only way to know WHY the airlock is bubbling is to take readings.

Well, as Alice said, "curioser, and curioser". Went down to check on the stout to see if the new bubbling had stopped, and not only is it still bubbling, there is bubbly foam at the top which looks likes it is getting thicker. The batch did form krausen in the primary, which was absorbed before I racked to the secondary. It certainly LOOKS like it's fermenting again (though I won't know for sure til I check the gravity again in another day or so). I just worry that what I am seeing is a contamination doing this, rather than re-awakened yeast, though I was certainly careful that everything but everything was well sanitized with Star San. Very odd indeed.

rwberne said:

Well, as Alice said, "curioser, and curioser". Went down to check on the stout to see if the new bubbling had stopped, and not only is it still bubbling, there is bubbly foam at the top which looks likes it is getting thicker. The batch did form krausen in the primary, which was absorbed before I racked to the secondary. It certainly LOOKS like it's fermenting again (though I won't know for sure til I check the gravity again in another day or so). I just worry that what I am seeing is a contamination doing this, rather than re-awakened yeast, though I was certainly careful that everything but everything was well sanitized with Star San. Very odd indeed.

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Contaminations are really really really really rare, rarer than most new brewers may understand or belive...Take that off the table.

Read my answer and the links I provide here, When can I stop worrying about infections?

Okay, I got it - I won't worry that it's infected. I will RDW, and I will definitely have AHB. I appreciate your time and input!