20 gallons of stuck fermentation

So I brewed two different 10 gallon batches and now have 4 carboys full of beer stuck at about a full point short of full fermentation. One is an APA and the other is an oatmeal stout. I'm looking for a way to get these going again to get them to ferment out all the way.

I used California ale yeast in both and the yeast has come from previous batches in both cases and I think that may be the issue. If I were to grab another vial and make a 2L starter and then split it between the 4 carboys would that kick it into gear again to finish fermenting?

 

A few questions:
When did the fermentation start, and how long did it last?
What SGs are the beers at and where do you think they should be?

 

How old was the yeast? How strong was the last beer you used that yeast for? How did you store it? Did you make starters?

Reusing yeast from previous batches usually works fine for most people, but viability can seriously, and unexpectedly. drop for a lot of reasons. Many breweries that reuse their yeast multiple times have labs to test viability and vitality on their yeast, and discard if it doesn't meet their standards.

On a homebrew scale, you can't easily do much testing, so it's mostly just hoping that the yeast will work like you expect them to.

 

What do you mean by a full point? .001?

 

The APA had a starting gravity of 1.061 and is at 1.024. The stout was 1.058 and is at 1.028. I would like them to be down to around 1.015 or so.

The first beer I used it with was the APA. It was actually two fresh vials of cali (two in each fermenter) I picked up in a pinch because I tried to make a starter with some other yeast but it didn't take off. That fermented for about 2 weeks in primary then racked that over to a secondary the same day I brewed the stout and used the slurry from the bottom of each ferementer to pitch into the cooled wort. It wasn't the whole thing though, maybe 2/3 of each one.

The APA has been sitting for 3 weeks now and the stout has been going for 9 days.

 

Did you oxygenate the wort before pitching?

 

I just shook the hell out of em.

 

Try to rouse them by swirling the fermentation vessel, or toss a packet of clean finishing dry yeast in (Nottingham or SAF 05)?

Oops you beat me to it..........shake the hell out of them I meant. :rockin:

 

Did you do a forced ferment test? I do one on every batch. It's the only way to know if your gravity issues are yeast-related or mashing-related.

http://www.maltosefalcons.com/tech/forced-ferment-test

 

I don't and have never tried that. Perhaps I will give it shot tonight. I have a 2L flask. Should I pull a sample and pitch some yeast and throw it on the stir plate for a few days?

 

You can use baker's yeast for it, if you have that, but brewers yeast is better. You want to massively overpitch. If the gravity doesn't budge, or only drops down a little bit, then you know it's the wort, and not the yeast.

 

Are you measuring final gravity with a hydrometer or refractometer?

 

Hydro

 

Would a 1L starter out of the fermenter with a vial of yeast be enough?

 

Have you checked it in 60 degree water? It should be at or damn near close to 1.000 with tap.

So many stuck at one time is crazy. Either something went wrong wuth the recipe or the yeast was no good.

 

I really feel it was the yeast. I under pitched by a lot in the pale ale and then used that same yeast in the stout.

The recipes I've used before and they were great and Im using a rims system now so the only difference is that I'm using pumps but that's it. I hit target OG and temps were all good too.

 

I just use 1tsp of baker's yeast in 1 pint of wort, and shake it up for a few days for it to ferment out.

 

I dont know. You said you used 2 vials in each 5gallon pale ale, so 4 total vials of Calufornia Ale. Seems freakishly unlikely to get 4 underattenuating vials. With the rims are you using a new or different way to measure temps?

 

I monitor temp the same way using the dial thermometer. I mashed them both at 155 for 60 min.

 

Without a forced ferment test, viability and vitality testing for the yeast, a dissolved O2 meter, we're all just guessing as to what's the issue. Conjecture is good, but data is better.

BTW have you checked the pH? CO2 in solution form carbonic acid, which lowers the pH during ferment, sometimes by a lot. A low pH could shock low-vitality yeast into a stuck ferment.

 

Nope, haven't checked ph. I'm going to do the forced ferment test and take some readings. If the gravity drops more ill male a starter and pitch more yeast. If it doesn't budge, ill prob just call it a day and bottle/keg it. It'll get drank either way.

Next batch ill do a forced ferment test at the beginning and make sure I have a healthy starter. I tried to do some experimenting with used yeast for these and it backfired.

Btw, I appreciate the input. I'm still a newb and need to come up with some consistent practices.

I'll report back by the weekend!

 

Double post... Phone is jacked up.

 

I know plenty of people reuse yeast with good success. The tightwad in me wants to reuse yeast, but the lazy part of me would rather just start with fresh yeast. I reused my yeast for a while, but then I realized that I seldom use the same yeast back-to-back, and the yeast I was washing and storing was losing too much viability sitting in my fridge for weeks.