Seal the secondary fermenter using the sanitized airlock and rubber stopper. Be careful not to force the rubber stopper in so far that it falls into the beer; this does happen.
The beer is now ready to be placed in a cool dark place once again. The beer now completes fermentation and begins to mature. Secondary fermentation at room temperature lasts for one to two weeks. Any longer and off-flavors can be produced from dying yeast.
Seal the secondary fermenter using the sanitized airlock and rubber stopper. Be careful not to force the rubber stopper in so far that it falls into the beer; this does happen.