When racking onto a yeast cake...

[nduetime]

When racking onto a yeast cake, should it be swirled around (ie. shaking the carboy violently like I would with first pitched yeast?)

 

[benbradford]

It is preferable to wash the cake so that you discard some of the trub and keep the yeast, but if you want to(and i have in the past), go ahead and rack on top, and swirl it to get the yeast acitve. It also helps oxygenate the beer for the yeast.

 

[rjsnau]

You may also want to check out mrmalty.com for the yeast calculator. If you rack onto the yeast cake you will be over pitching which can lead to off favors. It is best to save about a cup of the slurry , clean the fermenter, then add your new beer and cup of slurry. Make sure everything that touches the yeast slurry is sterile.

 

[nduetime]

I appreciate the replies benbradford and rjsnau. Also, thank you for the yeast calculator. So I had already racked onto the yeast cake before I made the original post. I was in the middle of brewing my second batch of beer for the night and had been away from the fermenter. When I had a little time to read the replies, I walked over to noticed it was already bubbling pretty good, ~one bubble/second. I decided to carefully swirl the carboy around to loosen up the yeast cake and trub at the bottom but not so much that it was splashing around. Another hour and it had a large krausen. I like this new technique. Thank you again.