# Secondary Fermentation



## masta (Jun 2, 2005)

The term "secondary fermentation" is a little misleading. The beer does most or all of the actual fermenting in the primary fermentor. Primary fermentors are made of either plastic or glass. Many recipes can be made using only a primary fermentor - this is called single-stage fermentation. 


Other beers are better with 2-stage fermentation, and you can use 2-stage fermentation all the time if you prefer. After fermenting for a while in the primary fermentor, the beer is transferred into a secondary fermentor. 


*Important Note:*_ Primary fermentors can be either plastic or glass. However, for secondary fermentation you really should have a 5-gallon glass carboy. That's because It is very important that there's no extra air space in your secondary fermentor! And glass is best because it doesn't allow oxygen to pass through it, like some plastic does. So for secondary fermentors, always use the appropriate size glass carboy, never a bucket or a too-large carboy._


*Why use a secondary fermentor?*


*First*, because the beer will be clearer when you bottle it, so there will be less sediment in the bottles. This is because the beer has a chance to settle again in secondary. There will always be a little bit of sediment in the bottles when using the natural carbonation methods popular with home brewers.


*Second*, because fermentation will be faster and more complete when using two fermentors.


Fermentation starts out quite vigorously, and then gradually tapers to a stop for a few days. After the peak of fermentation, inactive “spent” yeast settles to the bottom of the fermentor. This inactive yeast actually inhibits the yeast that is still active and trying to finish the fermentation.


When you “rack” your beer (transfer to a secondary fermentor) you leave the inactive yeast behind, and the physical motion of the beer drives some of the dissolved CO2 out of solution. This re-invigorates the fermentation, so that it finishes faster, and the beer will have fewer off-flavors. This is more important with very strong beers, and with many lagers.


*Third*, because you can leave your beer in secondary much longer than you can in primary.


If you leave your beer in primary for more than 2 weeks, all of the settled yeast starts to “autolyze”, which means the stronger yeast cells start cannibalizing the weaker ones. This gives you harsh yeast “bite” in the finished beer. But when you rack to secondary, most of the yeast gets left behind, so it is safe to let the beer settle and age after fermentation is complete.


This is useful for stronger beers that need aging to mellow their flavor, and for making lagers, in fact, the word “lager” means “to lay down” (i.e.: to age).


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## Quigs (Jun 2, 2005)

Hi masta, i just transfered my first batch to the glass carboy after 5 days in my primary fermenter. The instructions are very vague as to how long the second stage should be, i am making a traditional european bock, if you know how long the second stage should be i would appreciate the advice thanks.


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## masta (Jun 2, 2005)

I would say 2 weeks in the secondary is a good target. You want to give it time settle and complete the last of the fermentation. You just don't want to wait too long because the last of the active yeast could become dormant and you will have trouble with carbonation.


Use caution when racking from secondary and stirring in dissolved primary sugar as oxygen is the enemy now. Beer does not have any SO2 to protect it like wine. Just keep the splashing down to a minimum!


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## Quigs (Jun 3, 2005)

Ok well my primary fermentation was 5 days so i will let it settle in the carboy for another week. After the putting the priming sugar it says to allow up to 2 weeks, but how do you really know when it is done carbonating. One more question i know i ask a bunch, the instructions say to age the beer, after carbonation, up to 21 days once again its kinda vague. It says it depends on the kind of beer, well im brewing a bock which is a lager i believe so how long do you think it should be aged? Thanks again for the help


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## masta (Jun 3, 2005)

Your Bock is only a true larger if you used a larger yeast and fermented at cool temps &lt;60 degrees. Based on the 5 day primary I would say it really isn't.


After priming and bottling put the bottles in a room temp70-75 degree spot for2 weeks and then chill one and try it. The only way to test is to open one up and try it. If it isn't ready wait another week and try again.


Aging the beer will definitely help with the taste and give the fines more time to settle for a clearer beer. Once my beer is carbonated I put it in the wine cellar which is at 56 degrees. This helps to keep the beer for an extended time. I havesome Oktoberfest from last fall that is still awesome and super clear from sitting 8 months!


I use the same principle to age beer as wine...consitent cool temp and away from light!


*Edited by: masta *


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## Quigs (Jun 3, 2005)

Hey Masta, you advise above that"_Primary fermentors can be either plastic or glass. However, for secondary fermentation you really should have a 5-gallon glass carboy. That's because It is very important that there's no extra air space in your secondary fermentor!"_ well when i transfered over to the my 5 gallon carboy it didn't fill it up to the top should i be worried about that. thanks


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## masta (Jun 4, 2005)

I have made some batches and had some space in the secondary without any issues. When you rack from the primary the beer isn't completely done fermenting and the small amount of CO2 being released will blanket the beer and protect it. A gentle shake/rocking of the carboy will also help release some gas and push out the air. It also knocks down some fines that hang up on the sides and top of the beer.


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