Sierra Nevada clone is showing weird yeast inconsistency

[czarsketch]

Hello!

I'm doing a 10gal batch of Nierra Sevada (from this recipe) and everything on brew day went smoothly, although I went a little light on mash water because I had to physically move my brew pot and didn't want to kill myself, so I ended with 9.0gal instead of 10gal.

My OG was: 1.044, which is close enough for rock n' roll. I split the batch between 2 6.5gal plastic fermenters, one with 5.25 gals, one with 3.75 gals. Noticing this mistake, I split the yeast (2 packets of rehydrated US-05) and pitched.

The 3.75gal fermenter fermented extremely vigorously and tapped out in 48 hours, and the 5.25gal is still going after 5 days. The gravity of the smaller fermenter was 1.004, so things seem to have gone OK (and it tastes great), but I'm really curious about why given proportionally similar pitch rates the larger fermenter is lagging so much? Is there a way to prevent this in the future?

 

[czarsketch]

I should mention that this was done as a BIAB all-grain...

 

[Cyclman]

How did you split the yeast? Unless using a scale with highly mixed yeast, it would be difficult to pitch it exactly.

What will be more interesting is to see if the final flavors vary. If so, you can always mix the batches together, commercial breweries do this all the time.

 

[divrguy]

Hello!

I'm doing a 10gal batch of Nierra Sevada (from this recipe) and everything on brew day went smoothly, although I went a little light on mash water because I had to physically move my brew pot and didn't want to kill myself, so I ended with 9.0gal instead of 10gal.

My OG was: 1.044, which is close enough for rock n' roll. I split the batch between 2 6.5gal plastic fermenters, one with 5.25 gals, one with 3.75 gals. Noticing this mistake, I split the yeast (2 packets of rehydrated US-05) and pitched.

The 3.75gal fermenter fermented extremely vigorously and tapped out in 48 hours, and the 5.25gal is still going after 5 days. The gravity of the smaller fermenter was 1.004, so things seem to have gone OK (and it tastes great), but I'm really curious about why given proportionally similar pitch rates the larger fermenter is lagging so much? Is there a way to prevent this in the future?

I'm not sure I'm clear either. Did you rehydrate the US-05 (actually not necessary) and then do a down the middle split or try to do a proportional split? If you split it down the middle, it makes sense whats happening because you have more yeast cells in the smaller batch and its done. The bigger one will finish too. So, really no worries.

Another thing is that whenever I rehydrated yeast (I only did it twice in a couple hundred batches) I noticed it got all stuck to the sides of my cup and unless I dunked the whole cup in my wort, i would have a lot of lost cells. So, I dunked. If you rehydrated 2 packs in one container, you my have gotten a disproportionate amount of cells in one vs the other even if you tried to make it even?

So, two containers or one?

 

[czarsketch]

I did a proportional split from a single container. I didn't dunk it, but I did rinse the container with sanitized cooled water. I guess you're right-I should just taste them. Thanks!