The secondary is often called the "brite tank" where the particulates in the beer settle out and "brighten" or clarify the liquid. Not a great lot of actual fermentation goes on there. Many brewers find the "brite tank" unnecessary. I use one as a practical matter: my fermenter is a 6 gallon Better Bottle, while the secondary is a 5 gallon BB. If I want to ferment another brew, I've got to put the other stuff somewhere, and it's not ready to bottle yet.
glenn514
