Fermentis Interruptis, or Men Who Stare at Airlocks

[jcarruth]

I have a batch of amber/dark beer that has been in the 2ndary fermentor for over two weeks. When the airlock flattened out, I took a gravity reading, thinking that I will be taking another gravity reading in a couple of days, to see if the beer is ready for bottling.

Then the airlock started up again, so I figure the yeast has more work to do. This airlock flattening and starting up again is a pattern I have not seen before.

The question: Is this a sign of something to worry and/or do something about (like pitch more yeast), or should I just let the process proceed until the lock flattens out for good, no matter how many ups and downs it has along the way?

The initial fermentation was very robust, so I have no doubts that there’s always been plenty of yeast working in there. I am just not familiar with this stopping and starting of fermentation activity.

Technical details: The O.G. was 1.040, and the final target gravity is 1.010. My last reading was 1.011. I am using a lager yeast, Saflager 34/70. Fermenting temperature has been on the warm end.

Update: Michael Tonsmeire (the mad fermentationalist) wrote me and said that gasses coming out of the wort don’t matter, just the gravity reading. I have always been taught to wait until the airlock flattens first, then think about bottling.

Thanks,
jcarruth

 

[jtratcliff]

I always like to post this video in "airlock as measure of fermentation" threads....

[ame]https://www.youtube.com/watch?v=4jzT_KTTZ0Q[/ame]

Many different things can cause a bubble in the air lock, not just fermentation... The gravity reading
(same reading over several days) is the only way to really know when you're done.

 

[Sammy86]

The air lock unfortunately isn't an indication of fermentation...the only true way to know if by taking a gravity reading...

If your readings are the same 3 days in a row you are safe to package the beer.

 

[cloudybrewer]

Could be CO2 coming out of suspension due to temperature changes. Someone mentioned that on a similar thread. Sounds plausible, I guess.

 

[lschiavo]

Set it and forget it...your calendar for 4 weeks or so. Give yourself a few weeks to get around to it. It will be done by then without any help from you at all

 

[jtratcliff]

Could be CO2 coming out of suspension due to temperature changes. Someone mentioned that on a similar thread. Sounds plausible, I guess.

yup... Temperature changes, or changes in atmospheric pressure when a weather front moves through...

Once equilibrium is disturbed, outgassing can occur.