Stuck/Stalled/Conked Altbier

Here are the vitals:

Grain Bill:

8.00 kg (17.6lb) Munich (BestMälz) (15.0 EBC) 86.6 %
0.44 kg (15oz) Munich Dark (BestMälz) (25.0 EBC) 4.8 %
0.40 kg (14oz) Caramunich I (Weyermann) (100.5 EBC) 4.3 %
0.20 kg (7oz) Carafa Special II (Weyermann) (817.5 EBC) 2.2 %
0.20 kg (7oz) Caramel Pils (BestMälz) (3.0 EBC) 2.2 %

Batch size: 42L (11 gallons)
Single infusion mash 60mins @ 68C (154F)
Pre-boil gravity: 1.045 (target: 1.046)
60 minute boil
Chilled to 15C (59F)
Post-boil gravity: 1.053 (target: 1.051)

Decanted and pitched 2L starter of WLP029 (Kölsch) to 15C (59F) wort.
Fermented at 15C (59F) for 5 days. Healthy krausen observed on days 3 and 4.
Ramped temperature up to 20C (68F) over 24 hours.
Stayed at 20C (68F) for 3 full days (until today).
Took first post-fermentation gravity reading today and got 1.021 (target: 1.014).
7 points out. Not good.

Did I under pitch the yeast?
Did I start fermenting at too low a temperature?
What can be done?

I am tentatively planning to raise the temperature of the batch back up to 20C (68F) and rouse the yeast back into suspension. Maybe leave if there for another week, take another reading.

Any thoughts or wise advice would be appreciated. It’s my first time with a stalled fermentation.

1) What was your grainbill ?
2) Are you measuring gravity with a hydrometer or refractometer ?
3) is your measuring device calibrated correctly?

I would tentatively say warm it up and let it ride, 8 days might be a little short at those temperatures.

Grain Bill:

8.00 kg Munich (BestMälz) (15.0 EBC) 86.6 %
0.44 kg Munich Dark (BestMälz) (25.0 EBC) 4.8 %
0.40 kg Caramunich I (Weyermann) (100.5 EBC) 4.3 %
0.20 kg Carafa Special II (Weyermann) (817.5 EBC) 2.2 %
0.20 kg Caramel Pils (BestMälz) (3.0 EBC) 2.2 %


I'm using a hydrometer. I have used it successfully for previous batches and it's not damaged.

Thanks for your suggestion. I guess I'm mainly wondering if the yeast will become active again in the presence of however much alcohol has been produced thus far...

how accurate is your thermometer? any chance your mash temp was a little high resulting in some unfermentables?
fwiw, I usually mash my altbier @ 152

thermometer has been reliable with previous batches.
re-calibrated today just to be sure. it was only out by 0.5C in ice cold water. not enough to throw the gravity out by 7 points i wouldn't think.

I've read of kolsch yeast being slow to finish. maybe it'll kick off again.

I have BeerSmith for my recipes so I just recently started listening to their podcasts. They have two podcasts about brewing High Gravity Beers that I recently listened to and mention some tips with Fermentation and Stuck Fermentation. Some of the information may still apply to your situation even though it isn't high gravity. Rousing the yeast was one tip and if I remember correctly using a wine/champagne yeast to finish since it is a clean yeast, finishes dry and does not provide any fruity esters and such. They have other tips as well. Never had a stuck fermentation, but might be worth investigating and I am going to refer back to them if I ever have a problem.

I'm not sure if I can provide the links since I haven't posted until recently. Episode 33 and 117 are the ones and the podcasts are on youtube.

Good luck, hope this helps, and let us know how it goes.

thanks for all the opinions and suggestions so far.

I'm going to do up a big starter of WLP029 this afternoon. Pitch tomorrow morning at 18C (64F). I feel the combination of rousing, re-pitching, and optimum ale temperature is a "cover all bases" approach.

I have read that WLP029 is a clean yeast, even at regular ale temperatures. The gravity reading suggests that i have achieved 82% of my target attenuation. Would I be mistaken in thinking that esters may not be that big of an issue with that amount of remaining fermentables residing?

Just to report,

My efforts to finish the fermentation failed.

Still getting a reading in and around 1.020 (far too high for a beer with stated grain bill).

I think I will bottle anyway. Probably open a test bottle every couple of days for bomb detection.

Shtumbles_McShlurrin said:

Just to report,

My efforts to finish the fermentation failed.

Still getting a reading in and around 1.020 (far too high for a beer with stated grain bill).

I think I will bottle anyway. Probably open a test bottle every couple of days for bomb detection.

Click to expand...

Adding a teaspoon of alpha amylase (AA) and waiting a week would bring that FG down. I'd put money on it. Your local homebrew shop should carry.

See this: Escape from Stuck Fermentation Mountain - AE to the Rescue!

passedpawn said:

Adding a teaspoon of alpha amylase (AA) and waiting a week would bring that FG down. I'd put money on it. Your local homebrew shop should carry.

See this: Escape from Stuck Fermentation Mountain - AE to the Rescue!

Click to expand...

Guess I'll be making a trip to the LHBS today! I have a chocolate stout stuck at 1.030 (should finish around 1.015) and already tried raising the temperature from 68 to 71 F and then pitching another fresh packet of WLP001.

passedpawn said:

Adding a teaspoon of alpha amylase (AA) and waiting a week would bring that FG down. I'd put money on it. Your local homebrew shop should carry.

See this: Escape from Stuck Fermentation Mountain - AE to the Rescue!

Click to expand...

Thanks for the link! Some great information I was completely unaware of.

I dumped a 5g sachet of pilsner enzyme into each fermenter yesterday. Any info on pilsner enzyme vs. alpha amylase?

Already saw some krausen activity. Looking positive thus far.

Will report back in a few days with a gravity reading.

Took a gravity reading today, three days after pilsner enzyme addition.

Altbier has reached the target FG of 1.014

There is still some foam on top (uniform bubbles which look more like carbonation than sporadic krausen). I'll wait another few days and check for a stable reading before crashing.

It's been one week since the Pilsner enzyme addition and the gravity has dropped further to 1.010

Now I'm faced with another dilemma. The beer is supposed to finish at 1.014

Fermentation also appears to be still active.

That is the problem with alpha amalyze during fermentation - how do you stop it?

LKABrewer said:

That is the problem with alpha amalyze during fermentation - how do you stop it?

Click to expand...

You don't. You're going to get 85% - 90% attenuation when you add it. Not ideal, of course, but fixes an undrinkable (way too high FG) beer. Finishing low isn't such a big deal IMO. Finishing too high though, that's undrinkable (for me).

To be complete, I guess you could remove the yeast (filter @ 1 micron) or kill the yeast (heat to 120F). I wouldn't bother though.

passedpawn said:

To be complete, I guess you could remove the yeast (filter @ 1 micron) or kill the yeast (heat to 120F). I wouldn't bother though.

Click to expand...

Yea. It's all about making the best of an undesirable situation at this point. Leaving it run the course is by far the most appealing option.

Gravity reducing further still, two weeks on from enzyme addition. Measured 1.006 today. Bubbles still rising.

If anyone is in the same boat as me reading this thread, I wouldn't recommend adding enzymes. I had a bad conversion in the mash that left my beer six points above where it was intended to be, but drinkable as I had gone for high hop bitterness.

Following the enzyme addition, the beer was eight points below where it was supposed to be at the last reading. Now it tastes far too dry and bitter. I decided to bottle it, as I needed the chamber and vessels for a new brew. Active fermentation was still observable in the form of occasional rising bubbles, so it may well be the case that I am sitting on bottle bombs. In hindsight, I should have bottled the beer that finished too high. It tasted far nicer than what I am left with. The enzyme trick might work for other situations though.