Chapter 8 - Fermentation
8.4 Using Secondary Fermentors
Using a two stage fermentation requires a good understanding of the fermentation process, and should generally only be done if a second fermentable, such as crushed fruit, is being added to the beer, or the beer is being soured with a bacterial culture, or if the beer must sit on the yeast for a long time (more than six weeks) before being packaged. Racking the beer off the yeastbed before fermentation has completed can result in a stuck or incomplete fermentation. The less racking the better; because any oxygen exposure after fermentation is more than half done will promote staling of the beer. In most cases, it is best to let the fermentation finish, and only rack the beer to a bottling bucket or keg in order to package it.
The following is a general procedure for using a secondary fermentor, if necessary.
- Allow the main fermentation to wind down. This will be 2 - 6 days (4 - 10 days for lagers) after pitching when the bubbling rate drops off dramatically to about 1-5 per minute. The krausen will have started to settle back into the beer.
- Using a sanitized siphon (no sucking or splashing!), rack the beer off the trub into a another clean fermentor containing the secondary fermentable (depending on what you are doing it for) and affix an airlock. The beer should still be fairly cloudy with suspended yeast.
To repeat: only rack the beer to a secondary fermenter if you are conducting a secondary fermentation of the beer, or need to store the beer for a long period of time before packaging it.
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