Beer fermentation slowing down half way

[BeirKaiser]

I don’t know what to do as this has never happened to me. I’m fermenting a doppelbock (started 2/8/21) OG 1.080 and target 1.021. I did a two packet yeast starter with Servomyces pills. The graph above I made shows it’s slowing down way to fast. It’s about 50 seconds between bubbles. It’s at about 46% of the way (1.053). The kräusen has started to go less strong. What are my options? Open up the Servomyces pills? Pitch another yeast starter? Let it ride and hope it reboots? Thank you

 

[BrewZer]

View attachment 721653
I don’t know what to do as this has never happened to me. I’m fermenting a doppelbock (started 2/8/21) OG 1.080 and target 1.021. I did a two packet yeast starter with Servomyces pills. The graph above I made shows it’s slowing down way to fast. It’s about 50 seconds between bubbles. It’s at about 46% of the way (1.053). The kräusen has started to go less strong. What are my options? Open up the Servomyces pills? Pitch another yeast starter? Let it ride and hope it reboots? Thank you

So, what yeast did you supplement with the Servomyces? What temperature are you fermenting at?

 

[BeirKaiser]

So, what yeast did you supplement with the Servomyces? What temperature are you fermenting at?

Wyeast 2206 Bavarian lager and its being held in my basement between 48-52 degrees. The yeast has an upper limit of 60

 

[VikeMan]

How long ago was brew day? And how are you measuring gravity?

 

[BeirKaiser]

How long ago was brew day? And how are you measuring gravity?

Brew day was 2/8 so about a month ago and taking samples and measuring with a refractometer. I need to get it down to 1.026 before I can lager

 

[VikeMan]

Brew day was 2/8 so about a month ago and taking samples and measuring with a refractometer.

Are you correcting the refractometer reading with a refractometer calculator?

 

[Qhrumphf]

It's normal for fermentation to slow down after an early explosive burst. What's the timeframe? I can't tell from your picture.

 

[BeirKaiser]

Are you correcting the refractometer reading with a refractometer calculator?

It’s an ATC refractometer and both the refractometer and the sample are at room temperature

 

[Qhrumphf]

Are you correcting the refractometer reading with a refractometer calculator?

Missed the boat. Yes, this.

 

[VikeMan]

It’s an ATC refractometer and both the refractometer and the sample are at room temperature

You need to use a refractometer calculator. Alcohol skews any readings after fermentation starts. And even the "OG" reading needs to be adjusted for the fact that wort sugars are not mostly sucrose.

 

[Qhrumphf]

It’s an ATC refractometer and both the refractometer and the sample are at room temperature

Are you correcting for ethanol? A refractometer will not read correctly when ethanol is present (changes the way it refracts light). Either use a corrective formula (Terrill or Novotny calculators available online), or use a hydrometer (or if you've got money there's more advanced methods/devices but they'll cost a few hundred to few thousand dollars).

 

[BeirKaiser]

It's normal for fermentation to slow down after an early explosive burst. What's the timeframe? I can't tell from your picture.

Put in the carboy on 2/8 so it’s been about a month

Missed the boat. Yes, this.

It’s an ATC refractometer and both the refractometer and the sample are at room temperature

 

[VikeMan]

Here:
https://www.brewersfriend.com/refractometer-calculator/Pop your original and most recent readings in this. And then (most likely) start lagering.

 

[BeirKaiser]

You need to use a refractometer calculator. Alcohol skews any readings after fermentation starts. And even the "OG" reading needs to be adjusted for the fact that wort sugars are not mostly sucrose.

It’s specially a wart and wine refractometer. Is there a place to convert?

 

[Qhrumphf]

Based on a (face value) 1.080 start and a current 1.053, and 1.00 corrective factor, your actual FG would be closer to 1.037.

 

[IslandLizard]

It’s specially a wart and wine refractometer. Is there a place to convert?

Refresh the page, the answers are right above your last post.

 

[Qhrumphf]

As for a wort corrective factor, you can use multiple worts of various gravities, verify with an accurate hydrometer, and get an average corrective factor. It's usually off by a couple percent but is specific to both your wort/equipment/process. The trouble is that the sugar composition of wort is variable based on a lot of factors (see above about your equipment/process) so a refractometer will ALWAYS be an estimate.

 

[BeirKaiser]

Based on a (face value) 1.080 start and a current 1.053, and 1.00 corrective factor, your actual FG would be closer to 1.037.

That’s what I’m coming up with too but that still seems too far away from my target for it to be going this slow. I’m fearing that I’ll gave to add yeast to my spiese and turn it into a kräusen just so I can bottle ferment two months from now

 

[IslandLizard]

That’s what I’m coming up with too but that still seems too far away from my target for it to be going this slow. I’m fearing that I’ll gave to add yeast to my spiese and turn it into a kräusen just so I can bottle ferment two months from now

I'd take a hydrometer sample to get an actual gravity reading, before doing anything.
You can easily suck-siphon a 3-4 oz sample...

How big is this batch and how many cells did you pitch?
Did you oxygenate?
Those could have something to do with the progression of your fermentation.

 

[Birrofilo]

Although this doesn't happen often, if you have a pH meter you could check the pH of the wort.
The high OG and the heavy lifting already made by the yeast might have lowered the pH of the wort too much and now the yeast is having trouble because the environment is too acidic.

If that's the case, you should add some sodium bicarbonate or some calcium carbonate to raise the pH and make the yeast happy again.

pH at around 4,5 at this stage of fermentation is probably too low. pH lower than that, let's say 4, is definitely iffy. pH is slowly lowered during fermentation. It should arrive to 4 - 4,5 at the end of the fermentation, not in the middle. pH below 4 might mean that is your problem I guess, but wait for somebody better informed than myself!

 

[Qhrumphf]

I'd be shocked if that were the case. Lager yeasts don't drop pH nearly as far as other yeasts, and OP is at a point in fermentation where I'd expect the yeast to be nearing the bottom of it's pH (before climbing slightly at the very end). I definitely wouldn't add any alkalinity to bring the pH up barring something extreme.

I would suggest letting your fermentation warm up. In addition to cleaning up any diacetyl it should help speed it along.