How Long Will This Keep Fermenting?

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Polkahero

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Just brewed my first batch last week and the yeast is still bubbling vigorously after 48 hours. Had to run a blowoff tube as it was a 5-gallon batch in a 5-gallon carboy. Just wondering how much longer it will ferment at this level and/or when I can remove the blowoff tube and put the airlock back on. . .
 

Yooper

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It will slow down, and then stop. It's hard to say when for sure- just when the yeast run out of fermentables to eat. It depends on so many things- the health of the yeast, the temperature of the fermentation, the amount of yeast pitched, the ingredients used, etc, that it's hard to say for certain. Generally, the bulk of fermentation is finished within 3-5 days, then the yeast finish up before starting to digest their own waste products.

Usually, fermentations in a cool place are slower than in a warm place. Higher OG wort (with more fermentables) can take a bit longer, and a big amount of yeast pitched can be different than a small amount of yeast.
 
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Polkahero

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It will slow down, and then stop. It's hard to say when for sure- just when the yeast run out of fermentables to eat. It depends on so many things- the health of the yeast, the temperature of the fermentation, the amount of yeast pitched, the ingredients used, etc, that it's hard to say for certain. Generally, the bulk of fermentation is finished within 3-5 days, then the yeast finish up before starting to digest their own waste products.

Usually, fermentations in a cool place are slower than in a warm place. Higher OG wort (with more fermentables) can take a bit longer, and a big amount of yeast pitched can be different than a small amount of yeast.
Interesting, digest their own waste products? How does that affect the taste/aroma of the beer?
 

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Interesting, digest their own waste products? How does that affect the taste/aroma of the beer?
It improves it! For example, yeast create diacetyl as a by product of fermentation. Some strains are notorious for producing more than others. After fermentable sugars are gone, the yeast then go back and digest some of these by products, like diacetyl.

That's why some of us talk about leaving the beer on the yeast cake after fermentation is over, even raising the temperature a bit near the end of fermentation to ensure that the yeast keep up this vital work.
 

wyzazz

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A lot of folks (including me) ramp up fermentation temperature after Active Fermentation is done to keep the yeast going and help them to clean up the byproducts of fermentation.
 
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