The Great Secondary (Fermentation) Debate

To outside observers, the idea that a humble 5-gallon (19-liter) glass jug could inspire heated debate might seem a touch preposterous. But many homebrewers form very strong opinions regarding the secondary fermentor. Some claim that the secondary is almost always necessary, while others brag about how many months their 1.112 (specific gravity) barleywine has been sitting on the yeast.

First of all, even though we all say it, secondary fermentation isn’t really the right term. Little to no fermentation actually takes place in secondary, which is why I often go out of my way to refer to this phase as conditioning, maturation, or lagering (in the case of the eponymous cold-fermented styles). Whatever you call it, secondary is simply the vessel to which beer is racked away from the yeast and trub that remain after primary fermentation is complete.

I am nothing if not moderate, so here are the arguments for and against, presented so you can decide which camp you fall into.

For

Those homebrewers who favor secondary fermentation offer some great reasons for racking to a carboy for bulk conditioning.

1. Moving homebrew off the yeast reduces opportunities for yeasty off-flavors such as those associated with autolysis.
2. Aging in a secondary results in clearer (brighter) beer.
3. Glass carboys are not oxygen permeable, making them the preferred vessels for long-term aging without oxidation.

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Against

Naturally, those homebrewers who prefer not to bother with a secondary vessel have some good points as well.

1. Racking is just another opportunity to introduce oxygen. Foregoing the transfer to secondary can delay the onset of stale flavors.
2. Leaving homebrew on the yeast for an extended period of time gives yeast an opportunity to clean up after itself, re-absorbing unwanted compounds such as diacetyl.
3. Bright homebrew can be achieved without transferring by simply giving yeast the time to drop out of suspension.

The Bottom Line

As with so many aspects of homebrewing, the decision to secondary or not is mainly one of personal preference. In my case, it often comes down to time constraints and the style of beer I’m working with. I never rack German Weißbier to a secondary carboy because the style is meant to be cloudy and yeasty, and Hefeweizen should be consumed early: no time to condition! But I almost always transfer high-gravity ales and lagers to conditioning vessels because these usually need to mature for several weeks or months, and I’d rather not risk the possibility of off-flavors.

I think the secondary debate isn’t really a debate at all. Leaving your homebrew in primary has a place and a time, as does transferring to a carboy for aging. If you’ve never tried a secondary phase, give it a go. If you’ve always secondaried, try bottling or kegging straight from primary. See what you think and let your observations take you the rest of the way.