Originally Posted by Jablestein
I did talk to someone who said they take the fermentation bucket and shake it every few days during fermentation. Anything wrong with doing that?
Yes, actually. By shaking the bucket, they risk oxidation. There is no advantage to it, and harm may be done.
If you've ever watched fermentation, it's quite active. The yeast are rolling around, even producing heat as they work. A krausen forms on top, but there is lots of activity under the krausen. The yeast know where the sugars are, and so there is no reason to agitate them.
Once fermentation slows, the yeast flocculate and fall out to the bottom. The yeast actually go back and digest their own waste products after the fermentable sugars are gone. After that, they go dormant, and the beer will start to clarify. Once the beer is clear, it can be racked and packaged.