The Conventional Wisdom
Most standard homebrewing books recommend racking your beer to a Secondary Fermenter once the fermentation slows a bit, in order to avoid off flavors that would otherwise result from yeast autolysis. For years, homebrewers have dutifully racked their beer from carboy to carboy, or from food-grade plastic bucket to carboy. Racking is considered especially important when using open fermentation in a plastic bucket (that is, the lid is placed on top but not sealed).
The term "Secondary Fermenter" is misused in the majority of cases. Fermentation takes place in the primary vessel which is a fermenter. The Secondary Vessel is used to condition and clear the brew as well as bulk age. In a few circumstances a Secondary fermenter is used when the brew is moved from the Primary fermenter to a second fermenter and new fermentables are introduced such as fruit. The correct term in the majority of cases for the Secondary Vessel is a Bright Tank.
Recently, however, some have questioned whether this process is necessary or beneficial. Some say that there is not enough yeast to create off flavors when working on a home brewing scale, or that any autolysis would be undetectable in any but the lightest beers or with any but the unhealthiest yeast.
This section is a stub.