Fermentation done in 12 hrs ???!!!

[Vetal]

I made a Guinness clone on Monday this week. I wanted to hit an OG of 1.048 ... but my efficiency exceeded my wildest expectation. Instead of getting a standard efficiency I usually get - around 75% - I ended up getting a 83% efficiency and an OG of 1.054... oh well. I cooled the wort down to about 70F and oxygenated with pure O2 for ~1 min (maybe slightly longer). I had a Wyeast 1084 Irish Ale yeast pack - expiry was March 2022 ... really fresh viable yeast. I pitched the yeast at around 9.30 pm at night without any starter - just a single liquid yeast pack.... left my fermenting bucket in the basement with an ambient temperature around 69-70F. This is where things get interesting. The next day - I came down around noon to check if the fermentation had begun... there was no airlock activity at all. I just assumed that the yeast were being "lazy" and gave it another 12 hrs... still no airlock activity. I checked the bucket lid and there was no air leak - when I pushed on the lid - I got bubbles coming from the airlock. It seemed pretty airtight. Finally today I took a flashlight and peaked in through the airlock hole and guess what - krausen had already fallen! Only explanation is that the fermentation had already passed its high activity phase in the first 12 hours after pitching yeast. I havent taken a gravity reading - but is it possible that the fermentation could have been completed in 12 hrs flat??? I have never seen fermentation complete so fast ever before.... Just wanted to know your thoughts and experiences.

 

[GoeHaarden]

I havent taken a gravity reading

...

 

[day_trippr]

I concur...

 

[Jayjay1976]

Without taking gravity readings, I've had fermentations finish within 30 minutes of pitching the yeast.. Evidenced by no airlock activity and no visible kraeusen. Weirdly, the next day it seemed to be enthralled in some sort of a secondary fermentation phase...

 

[bracconiere]

bottle it, and give it to people you don't like?

 

[Beerstein]

I’ve had fermentation finish really fast once, but maybe it was 18 hours. I use enzymes and mash low, so I usually 99% attenuation. It also bubbled like crazy.

this does not sound like your situation.

 

[BeerAndTele]

My plastic buckets were never truly airtight. I'd change lids & rubber gaskets but the airlock was never a great indication as to what was going on inside.

 

[Gilbert Spinning Horse]

I'd lay money on an air leak.