Wyeast 1084 (Irish Ale) - 2nd generation = Big attenuation?

[Josh S]

I recently brewed an Irish Red Ale, OG 1.052 @ 7.5 gallons using Wyeast 1084 (Irish Ale).

Since I had a nice big yeast cake and was curious how this strain worked with hop flavors, I used 1/4 of the slurry to ferment 5 gallons of extract IPA. I used only Briess Pilsen Light LME + a 1/2 lb of steeped C-40.

OG on this 5 gallon batch was 1.058; I expected an attenuation of 71-75% from Wyeast's specs. Instead, the beer bottomed out at 1.009 for an AA of 84% (!!!).

Has anyone else had a similar experience after reusing this strain?

 

[BugEyedValiant]

I have had the exact thing happen to me with this strain of yeast and I should have thrown it away. I kept reusing it to build starters and in my case it was the start of a bad string of infections. By the time I figured it out, I was getting sour beers in 2 weeks. I'm not saying that this is your problem, but it was the start of my issues.

 

[RM-MN]

As a brewer you get to make choices while making wort. The recipe is under your control as is the water and the boil. When you pitch yeast, you are no longer in control, the yeast are. Most of the time they work within the predicted range but sometimes they decide to do something different. This was one of those times. It might never happen again or it might happen the next 10 batches in a row.