Wlp925 stalled

[AlbertaBeer]

This is going to be long winded…

So I recently tried my first batch using wlp925 and things aren’t really going to plan…

First off, the yeast was a few months past the best by date, so I used both pure pitch pouches I had for this 5gal batch. Surprisingly fermentation took off relatively fast with the g4 up to 13psi within 24h and starting to vent. After about 2 days of what I would consider a normal amount of ‘action’ things slowed down to a crawl and by the end of the 4th day since pitching activity seems to have ceased

Of course like a total newb I was in a rush with this batch and didn’t get a starting gravity. But it is the same old recipe Ive used several times which consistently gets me 1.050-1.053

I pulled another sample today which is close to 2 weeks since pitched and about a week of no/slow activity. my sg is at 1.027 and the hydrometer is only showing about 1.5%abv

This is my first time using wlp925, so I’m not sure if it’s just a yeast thing or what I did wrong here. In the past the same recipe using wlp800 (at 10psi) has given me good results and usually takes close to 2 weeks to get down to 1.010

Any thoughts as to what to try now? Of course I’m all out of wlp925 to repitch. I do have some wyeast 2007 which of course is also a little outdated now too

 

[brechbräu]

When you sampled it, did you notice anything else “off”—smell, particulate matter, etc? Is it possible your batch picked something up or something in your process may have accidentally killed the yeast?

 

[IslandLizard]

Have you checked the calibration of your hydrometer?

I'm not familiar with this yeast, but reckon since it's a "lager yeast," it needs a larger pitch (twice of an ale yeast).
http://www.brewunited.com/yeast_calculator.php

If your hydrometer checks out, you likely underpitched, using 6-9 month old yeast, even when using 2 pouches. How was that yeast shipped (cold?) and stored (fridge)?
It's always recommended to make a starter with the yeast prior to pitching into a batch, so it can grow more cells that will also be in optimal condition.

Fermenting under pressure suppresses activity and stresses yeast, so that's not helping your case either, even at higher temps (which increases activity).

Do you have more yeast available to make a big starter from, and pitch that in hopes of resurrecting this batch?

BTW, your alcohol % is much higher than you "read" on your hydrometer:*
1.050-1.027 = 0.023 * 131.25 = 3.01% ABV (!)
https://www.brewersfriend.com/abv-calculator/

* That scale is misleading and cannot be used (read directly) like that. It gives you a maximum alcohol % based on 100% attenuation, which is unusual for beer anyway.

 

[Bobby_M]

and the hydrometer is only showing about 1.5%abv

That's not how a hydrometer works. The ABV scale is "potential" ABV for wine when measuring pre fermentation must and that number is assuming it will ferment below 1.000

This is my first time using wlp925, so I’m not sure if it’s just a yeast thing or what I did wrong here. In the past the same recipe using wlp800 (at 10psi) has given me good results and usually takes close to 2 weeks to get down to 1.010

Any thoughts as to what to try now? Of course I’m all out of wlp925 to repitch. I do have some wyeast 2007 which of course is also a little outdated now too

Is this an all grain beer or extract?

 

[AlbertaBeer]

I’ve got a refractometer that is calibrated with bottled distilled water I had. Its readings seem to be on par with the hydrometer any time I’ve compared them side by side.

This is an all grain, same thing I’ve done many times in the past with a single pack of wlp800 (albeit non “expired” stuff) and it’s always turned out good. I didn’t notice anything off as far as smell or anything in the sample I pulled, I just typically see a longer fermentation and after this much time a lot lower SG with the wlp800

I can’t think of anything else that may have gone different here from my past batches. Maybe this yeast needs a bit of time to build up before cranking the pressure up? In the past even with the wlp800 I’ve always just set the spunding valve around 10psi and once it starts blowing off I set it up a few more pounds