Yeast waking back up suddenly?

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pabrimmer

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Has anyone ever seen their yeast enter a second period of visible activity after having initially calmed down? The only reference I've been able to find was in the online version of How to Brew where it turned out a toddler was dropping crayons and things into the fermenter. For the record, I do have a toddler, however the fermenter is well out of her reach in a closet!

I had about two days of vigorous activity after pitching, then several more days of slowly diminishing visible activity where the wort was very opaque and there was a steady flow of tiny bubbles. After that died down, the beer looked clearer every day, and at the two weeks mark, I was thinking it was about time to bottle. Then, one day, it was suddenly visibly active again - the tiny bubbles were back and the wort was very opaque again. It diminished over the next few days, and now I'm at three weeks. I'm going to go ahead and bottle now, but I'm just curious if anyone else has seen this behavior.

This is my first brew by the way. It's a 1-gallon kit from BBS - grapefruit honey ale. I'm just following their instructions, so I don't have all the readings or temperatures to share.

Cheers!
 
I would check, but I don't have any of that equipment. The BBS recipes rely on rules of thumb and I'm just going with that for the time being. If brewing turns into a steady hobby I'm sure I'll have a hygrometer or refractometer eventually.
 
what you are describing could be yeast starting back up...could be nothing...one way to tell. I hate it when someone asks a question and gets 20 answers with advice and none answer the question...but in this case again I would hold off on bottling and get a hydrometer and sample tube.. they are cheap and if you do have fermentation kicking back off and you bottle it you could get bottle bombs...trust me a hydrometer is cheaper than a trip to the hospital....
 
A more logical explination would be that the CO2 that was dissolved into the beer during the fermentation process was off-gassing out of the solution. That can happen if the temp changes slightly or if the pressure changes slightly.

For the most part, yeast are like dogs, if there is food in their vicinity, they WILL find it and eat it. Stories you hear about yeast falling out before fermentation is complete, i.e. stuck fermentation, results from an external variable that stresses out the yeast, like a high ABV environment or low/high temps, rapid changes in temps, etc..

Your fermentation sounds like it is fairly typical. If there was not some variable out of wack, you likely just had off-gassing of the CO2 in solution.

All that said, remember going forward that an airlock DOES NOT measure fermentation. A hydrometer measures fermentation. A bubbling airlock just tells you that some sort of gas is pushing through the resistance of the liquid in that airlock. A hydrometer measures the density of the wort relative to water, so it tells you definitively when the denser sugars in the solution have been converted to less dense alcohol and CO2.

Hope that helps!!!
 
A more logical explination would be that the CO2 that was dissolved into the beer during the fermentation process was off-gassing out of the solution. That can happen if the temp changes slightly or if the pressure changes slightly.

For the most part, yeast are like dogs, if there is food in their vicinity, they WILL find it and eat it. Stories you hear about yeast falling out before fermentation is complete, i.e. stuck fermentation, results from an external variable that stresses out the yeast, like a high ABV environment or low/high temps, rapid changes in temps, etc..

Your fermentation sounds like it is fairly typical. If there was not some variable out of wack, you likely just had off-gassing of the CO2 in solution.

All that said, remember going forward that an airlock DOES NOT measure fermentation. A hydrometer measures fermentation. A bubbling airlock just tells you that some sort of gas is pushing through the resistance of the liquid in that airlock. A hydrometer measures the density of the wort relative to water, so it tells you definitively when the denser sugars in the solution have been converted to less dense alcohol and CO2.

Hope that helps!!!

Great answer.

A bubbling airlock means virtually nothing. There is a video of a carboy that is empty with a bubbling airlock. This can be caused by temperature or pressure changes.
 
Thanks guys! I went ahead and bottled it last night, so we'll see how it turns out in a few weeks. There was a bit of a cold snap here in Texas right when the fermenter "woke back up" so that makes sense as far as a change in temp or pressure causing the co2 to leave.
 
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