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Sluggish fermentation for high gravity stout

So, I brewed a 1.125 OG stout the other day, with a starter of 2L. I two-stepped the starter in order to get it bigger on a stir plate, aerated the wort for 30 minutes, then pitched the starter in the wort 2 days ago. Mashed in at 147 for 60 minutes to get the beta amylase enzymes activated for a very fermentable wort. It is now fermenting at 69 degrees.

The fermentation seems extremely sluggish after two days, especially when looking at pictures of other people’s exact same recipe. Only got about 1 inch of krausen on top of the wort, compared to some people who appeared to have the same amount of krausen as fermenting beer in their primary. The yeast I am using is WLP099. I am pretty sure I under pitched…

I feel like I am about to have a stuck fermentation on my hands, so I wanted to ask some of you experts what you would do. Here are some of my questions:

  1. Should I wait for fermentation to end, transfer to seconday, and add like a 3 gallon starter?
  2. Should I aerate the fermenting beer right now before fermentation stops?
  3. Possibly add nutrients?
  4. All of the above?

Thanks guys!

RDWHAHB! It is fermenting. Your assuming it will get stuck. Let is sit for a week and take a gravity reading every day for a few straight days. If it keeps going down, then it’s still fermenting. If it stays the same and is in the FG range you were expecting, your good. All fermentations are different. Don’t create a problem before there is one.

Yep, you under-pitched by about 50%. As cheap insurance and to eliminate the worry, I would rehydrate two packs of US-05 and pitch (rehydrate to make the yeast drop through the krausen and give them the best chance of survival in the high-grav, alcoholic environment). No need to aerate or add nutrients either.

Hey thanks for your guys’ input. I’ll be taking advice from both of you! Picking up us-05 tomorrow, then drinking homebrew while doing so.


As a follow up:

I pitched us-05 yesterday, and the big beer seems to be fermenting like a champ. Lots of bubbling in the blow off tube, and a swirling and churning of yeast in the beer itself. Which led me to a conclusion: That it has been fermenting fine all along, just with little to no krausen.

Now I have heard that this could be due to the extreme amount of foam caused when I aerated the beer, and that it did. The beer actually foamed up so much (half of the carboy), I had to prematurely shut off the aerator before it started spewing out of the carboy. I read it somewhere that it can break up the proteins which form it.

I wonder if this is what happened to me?

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