Kick starting a stalled fermentation

I had a stalled fermentation so I boiled up some DME with yeast energizer, yeast nutrients, added it to my fermentor, and pitched some re-hydrated dried yeast. This was Friday evening. I'm not seeing any foaming and the air lock is not very active, but there is a layer of sludge at the bottom. Does the layer of sludge indicate there is fermentation going on or is that just yeast settling to the bottom?

The sludge does not mean anything: it could just be the proteins you precipitate during hot and cold breaks.

Many things can cause a stalled fermentation. So we'll need to know a bit more about this batch before we can really help you:

• Have you used your hydrometer?
• What yeast are you using?
• What temp are you fermenting at?
• What was the Original Gravity?
• What was the gravity it stalled at?
• What is the expected FG?
• Was it all grain or extract?
• Have you used your hydrometer? (yes - its in twice 'coz it's important!)
• How long had it been going before it stalled?

In general (if it really is stalled), warming it up and gently rousing the yeast (stirring with a sanitized spoon) can help. Ignore the airlock though: your hydrometer is your only true guide.

Welcome

Good post above by BioBeing, he nails all the points to consider. I recently had a stuck fermentation that rousing the yeast wouldn't resolve so I threw in 4 tablets of beano and a new pack of S05 and that did it. It was a 1074 OG that stalled at 1040 and now it's sitting at 1006. I still need to rack it to a keg so I can't say for sure if it's any good but the hydrometer says it's done...

Thanks for the responses:

I did an extract scottish smoked ale, 8 lbs of extract, steeping grains and white Labs Edinburgh yeast and nutrients - no starter. Yes, I use a hydrometer.

OG was 1.050. It had lots of visible activity for about 4 days - after three weeks at about 66 degrees, it was "stuck" at 1.028 for three days. (tastes overly sweet.) I swirled it and warmed it up and gave it another week but there was no change.

As for expected FG - the recipe did not have one but I was figuring on 1.018 at the high end. For repitching, I used safale S-33 .

Has the gravity dropped since you added the additional yeast? You said "the air lock is not very active", which indicates to me it is a little bit active? You don't necessarily expect to see a new krausen on repitching. The yeast are not actively growing as their is no oxygen and there are not that many sugars left for them to eat anyway.

1.018 sounds reasonable for Edinburgh, maybe even a touch lower (70-75% attenuation; 70% would put you at 1.015).

What temp do you have it at now? I'd try to get it to the low 70s, just to give the yeast as much chance as possible. There is really no worry about off flavours now that the initial phase is over.

Also: 8lb of extract might give you a higher OG than 1.050. Extracts are usually pretty much spot on, assuming that all the top up water got mixed in thoroughly (which is actually quite hard to do).

8 lb of Liquid extract into 5.75 gallons should give 1.050. If you used dry extract, you would need to be getting 7 gallons into the fermenter to hit 1.050.

8 lb of dry into 5 gallons would give an OG of around 1.070; which might finish up at 1.021 (70% attenuation).

I haven't done another reading since re pichting - I thought I'd give it a few more days. Maybe I will tonight. I keep forgetting that I probably won't get a full-on krausen explosion. Thanks for the help. Biobeing.

What's the Beano for?

Irrenarzt said:

Good post above by BioBeing, he nails all the points to consider. I recently had a stuck fermentation that rousing the yeast wouldn't resolve so I threw in 4 tablets of beano and a new pack of S05 and that did it. It was a 1074 OG that stalled at 1040 and now it's sitting at 1006. I still need to rack it to a keg so I can't say for sure if it's any good but the hydrometer says it's done...

Click to expand...

Beano contains amylase which is an enzyme that breaks down larger sugar chains into smaller ones, thereby making the remaining sugars in the wort more easily fermentable. You can also buy it labeled as amylase enzyme at your LHBS.

Hi All,

Looks like a timely thread for me. I'm a newbie, my first batch a porter turned out well, very drinkable, not amazing but oh well I'll get better.

My second batch is in the fermenter now. I brewed sunday, a fat tire imitation recipe from a book. Roughly 1 Lb of grain steeped, with 4.4 Lb of liquid extract and not quite 3 Lb of dry extract. My OG was 1.040 which surprised me, I thought, and my brewpal app told me 1.055 but 1.040 was what I ended up with. I pitched the yeast a wyeast 1726 Belgian Abbey 2, and the packet felt like it was about to explode when I opened it. The fermentation SHOT off, airlock was bubbling like a tommy-gun. Its three days later and no action for the last 2 days, I still had a good seal so I opened up and checked, I'm at 1.020. I was expecting my final grav. to be at least 1.010 or hopefully 1.005. While I had it open I stirred 10 good strokes with a sanitized spoon, and closed her back up. Any other tips, or when to check my grav again? Or is it RDWHAHB time?

-T

3 days? Leave it.

What temp is it at though? If it got chilled, you might want to warm it back up.

Well it sounds like a case of the 1020 blues yet again. Extract brews are less fermentable and so 1020 is a common FG. I would let it sit and let the yeast do their job. 5 days isn't enough time in most cases.

I checked again today, day 6. Still at 1.020. I agree that 3 or even 6 days is too early to worry. Just didn't know if there were proactive steps to take. I have the temperature up from 64F to 68-69F now. Hopefully if that was the issue it will take care of itself, if not I can deal with a lower abv. as long as it turns out well. Thanks for the suggestions!

-T

Interesting thing is I have a 10 gallon batch of Scottish 80 in the fermenter now with the same problem. I also used White Labs Edinburgh yeast (2 vials into 2 quart starter). It started at 1.049 and stalled at 1.020. Estimated FG was 1.013. It was fermenting strongly at 62 degrees the first three or four days, now its been sitting dormant at 68 for over a week.

After trying warming and stirring, I made another 2qt starter, this time with 2 packs of rehydrated S-05 (I wanted to bring the big guns). Once the starter was going, I added about a cup of the scottish ale to the starter twice eight hours apart. This morning the starter was going strong and I pitched the whole thing.

I'll post an update, I have my fingers crossed.