Secondary Fermentation

The term Secondary Fermentation typically refers to the period post-primary fermentation where beer is transferred from the primary fermentation vessel to a “secondary” vessel and given additional conditioning time.

However, as the circumstances of brewing and materials available have changed, so have opinions on secondary. Transfer to a secondary vessel is largely considered unnecessary, and some brewers consider it risky. In most circumstances Secondary Fermentation can be translated as “The period after primary fermentation has ended and before packaging (whether kegging or bottling).”


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his isn’t to say that there aren’t times when a secondary vessel is beneficial. Before making a judgment, it is important to understand Secondary Fermentation, its roots, and its affordances.

Why were secondary’s originally used?

The practice of secondary fermentation originally had a couple of primary purposes. The first was to prevent off flavors due to autolysis. In the earlier days of homebrewing there were less strains of yeast commercially available to homebrewers and that yeast wasn’t as viable and healthy as it is now.

Autolysis is a common cause of off-flavors in beer, and is caused by dead yeast cells rupturing. So, less vital, less healthy yeast meant an increased chance of autolysis, and so transferring the beer off of the yeast into a secondary vessel was one way to prevent those cell ruptures from producing off-flavors in the beer.

Another reason for using a secondary was for clarity purposes. Taking the beer off of the yeast and allowing additional time for matter to settle out of the beer resulted in; you guessed it, a clearer beer.

Finally, a secondary fermenter was often advocated for during the use of fruit, dry hops, or other additions post-primary fermentation. Because of the shape of most fermenters (think carboys), just dropping fruit or pieces of wood into the fermenter can cause splashing and oxidation. Carefully racking the beer into a new vessel that already contains the new additions can help prevent this oxidation.

Why shouldn’t we be using secondary anymore?

The concerns that originally led to secondary fermentation are valid, but the homebrewing world has changed significantly over a short period of time. Autolysis is no longer as great of a concern for the average homebrewer. Yeast is healthier and more viable. Our fermenters are (typically) not close to the scale of a commercial brewery and the pressure on the yeast isn’t nearly as intense. As such, autolysis is not as common as it once was. John Palmer and Jamil Zainasheff in the March 22, 2010 episode of Brew Strong say that leaving beer in primary for a month is fine and that modern fermentations are healthy enough that neither of them advocate for the use of a secondary vessel any longer (Zainasheff 2010). I’ve personally left beer on the yeast in the primary fermenter for five months with no problems at all; healthy yeast has really changed the brewing game.

Secondary FermentationAs for clarity, there just isn’t enough evidence to back up the claim, or at least, not enough evidence that clarity is a result of using a secondary vessel. If you give the beer more time, then more yeast will drop out, and you will get a clearer beer. In an exBEERiment, Marshall Schott of Brulosophy tested whether or not the use of a secondary affected clarity, and most testers found no discernible difference between the two batches. Some people still argue that using a secondary fermenter produces a clearer beer, I recommend testing both out and seeing which method you prefer.

For some additions I agree it is appropriate to rack to a new vessel. I wouldn’t want to dump a bag of cherries into a carboy, too heavy. Dry hops, however, go straight into the carboy and many brewers have no problems at all with this method.

Here is the major problem with using a secondary: Off-Flavors. Removing the beer from the yeast before fermentation is fully finished means that the majority of the yeast won’t be able to help in the processing of chemicals that cause off flavors like diacetyl. Transferring also increases the risk of contamination and oxidation, since you are exposing your beer to more equipment. Obviously this can be avoided with careful technique and sanitizing methods, but the increased risk isn’t worth a method which may not produce a better, clearer beer. For most beers, a secondary vessel is entirely unnecessary, possibly detrimental, and not beneficial in any way.

So when should I use a secondary fermentation?

There are a few times when using a secondary is the best choice:

  • When you are bulk aging for an extended period of time. While autolysis is not nearly as much of an issue as it used to be, it is still a possibility, and leaving a beer on the yeast for a long time can certainly cause it. Like I said, I’ve left beer on the yeast for five months with no off-flavors, but that may sound too risky for some brewers. Palmer and Zainasheff say that a month is absolutely fine, and so a month is a good number to start with. Bulk-aging for a month or two? No need for secondary. Longer? That is up to you, but eventually autolysis will be an issue.
  • When using large additions in a bottle-neck carboy. Cherries, raspberries, oak cubes, just dropping these things through the neck of the carboy can cause some oxidation issues from the splashing and oxygen exposure. Racking onto these additions in a secondary vessel may be a safer option. If you have a bucket as your primary fermenter, just gently add the additions since you have more space to get them closer to the liquid.

Hopefully the information here has helped inform you not only what Secondary Fermentation refers to, but the affordances of using a secondary vessel in your brewing.

Happy homebrewing!

Matt Del Fiacco is a homebrewer with a passion for community, high-gravities, and wood aged beers. Take a look at him and his other work at his blog To Brew a Beer

Zainasheff, J. (Narrator) and Palmer, J. (Narrator). (2010, March 22). Brew Strong: Bottling and Kegging [Radio broadcast episode]. In Brew Strong. Web. Retrieved from:

Schott, Marshall. (2014, August 12). Primary-only vs. Transfer to Secondary. Brulosophy. Web. Retrieved from:

written by Matt Del Fiacco

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8 comments on “Secondary Fermentation”

  • Mike Salsbury June 11, 2016 at 7:17 pm

    Great post, Matt. I started out extract brewing and even all-grain brewing without transferring to a secondary - ever. Then I kept making recipes that included a secondary step, and I started doing it then. I have to say that I agree with the experts quoted. I've not been able to see a difference between beers where I've racked to secondary and ones I haven't, with the exception of an extreme extract beer I made recently that ended up over 12.5%. That would did improve with a secondary and even tertiary transfer to get sediment out of it... probably due to the extreme amount of ingredients. The other beers I've made, couldn't tell a difference. The risk of contamination alone is worth leaving it in the primary as far as I'm concerned. I've done that for as long as three months with no ill effects.

    • David Galdeen June 14, 2016 at 2:40 pm

      Typically with high gravity beers like the one you describe Mike, age is the key anyways as they simply need more time to condition and develop. I am curious if you would have just left it alone in the primary for an extended amount of time if it would have shown much difference.

  • Thanks for this article and the great news it represents. This knowledge totally changes how I look at making a batch of beer.

  • Thanks for the informative articles! keep them coming!

  • Thanks for this tidbit of brewing wisdom! I've been stuck in the secondary fermentation rut for years and have always thought it was lessening the overall quality of my beer. Guess what I'm not doing on my next batch?

  • Thanks for the article, this was great information for a new brewer such as myself.

  • Hmmm... I actually look forward to racking the beer out of the primary to the secondary because it gives me something to do a week down the road instead of my normal 2-weeks before bottling (I have a hard time patiently waiting). I'm brewing an Irish dry stout right now (put it in the closet last night) and the directions specifically say to rack it to a secondary fermentor. So, I'll probably go ahead and do that.

    Since I use the same type of fermentor (6.5-gal pail) for both primary and secondary, I may stop using the secondary and just brew in primary until bottling time. That way I could have two batches going at the same time (1-week apart or so) and not worry about drinking /sharing my homebrew too fast. I still need to share 3 bottles of my last batch and that will only leave me about 10. Funny how stingy you can get when a batch turns out really good. I want to drink and enjoy it as well as share it but not run out!

    If I keep the brews in the primary until bottling. a week or two after the first one's ready, I'll have the second one ready and that will give me a couple of drinking choices instead of just one...hmmm.

    • David Doucette
      David Doucette June 14, 2016 at 7:56 am

      The solution here is clearly to increase production beyond the amount you can drink yourself.

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