Reusing yeast cake question

[jasert39]

I am planning on reusing a yeast cake for the first time this week...I brewed a 4.3% pale ale about two weeks ago and am going to pitch an IPA that should come in at about 7% on top.....is that a big enough beer to step up to on the yeast cake? Thank you.

 

[BigFloyd]

If you're going to immediately (within a few hours) pitch atop the cake w/o harvesting, remove about 70% of it first to avoid over-pitching the second batch.

 

[michiganflyer]

Really? I didn't know you could have too much yeast.

 

[BigFloyd]

Really? I didn't know you could have too much yeast.

Unless you're tossing a really high gravity wort atop it, a whole yeast cake is indeed too much yeast. You should either harvest and pitch or adjust the amount of slurry by removing a portion of it (depending on gravity and on ale vs. lager).

There's a lengthy discussion of the topic here - https://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/

I'm not in the "never pitch on the yeast cake" camp, but I do believe that you should use the correct amount if you do so.