Racking Beer to a secondary fermenter is the process of transferring beer from one fermenter to another after the primary fermentation process is complete.  The primary purpose for racking beer is to improve clarity, age the beer for better flavor and in some cases protect it from off flavors produced by dying yeast.  Additional benefits behind racking include the ability to dry hop, check out How to Dry Hop? and bourbon barrel aging your beer.  The most important part of this process is to make sure the primary fermentation step is complete before racking.

How to tell when primary fermentation is complete?

On average primary fermentation takes about 4-6 days for ales and 4-10 days for lagers to complete.  You can confirm that primary fermentation is complete by noticing the activity on the airlock has slowed down to less than 2 bubbles a minute. With some beers both primary and secondary fermentation happen in the same vessel, check out our fermenting the beer article for more.  Our recipe page will tell you what fermentation process is recommend for each specific style and recipe of beer.

primary fermentation phase finished

primary fermentation phase finished

What type of fermenter to rack into?

The best vessel to use during secondary fermentation is with out a doubt a carboy.  Carboy’s tend to have less head space than a bucket for example, less head space is important to help prevent oxidation to the beer. Both glass and plastic(food grade) carboys work great, however the plastic carboys are safer and tend to have a larger opening making them easier to clean.

How to rack and for how long?

Racking into a secondary fermenter should be done using a auto-siphon if you are not draining out a bucket with a spigot.  Before starting anything make sure the carboy has been cleaned, sanitized and had enough time to dry.  Regardless of method make sure the beer is flowing smoothly and not guzzling or splashing at any point.  As a rule of thumb the higher the original gravity of the beer, the long the beer needs to stay in the secondary to reach peak flavor.  From what I have experienced for lighter pale ales about 2 weeks is usually optimal, and about a month for a dry irish stout or any stronger/darker beers.

stout being drained to secondary

stout being drained to secondary

Why should you not rack into a secondary fermenter?

Well after I convinced you it was a good idea for your beer and easy to do, here are a few problems with racking.  The process of racking into a secondary fermenter greatly increases your chances of oxidizing your beer or introducing contaminates.  Introducing oxygen or contaminates to the beer at this point could cause staling reactions that will be noticed in the flavor of the beer within a couple of weeks after bottling the beer / kegging. With all of that being said, its well worth the risk and completely necessary to rack beer if you are planning on dry hopping or barrel aging your beer.