Hey everyone. I boiled up a barleywine last Friday, aerated for a few minutes with a hand mixer, and pitched a 2.5L starter made with a 10.5g pack of dry yeast. I would have expected the fermentation to last quite a while on such a big beer, but after three days the bubbling has already slowed significantly. I’ve experienced this plenty of times with smaller batches, none of which have ever lasted more than 3 or 4 days. All of those beers turned out fine, but because of the high gravity, such a fast fermentation does have me a little bit worried. Should I be concerned? And, more importantly, should I be doing something to save the beer?
High Krausen on even a big beer can come and go pretty quickly if you pitch the right amount of yeast. You have to figure if you have twice the yeast working on twice the sugar there are the same amount of sugar molecules per yeast cell as there would be in a wort half the gravity. You caould always carefully take a gravity sample and see where you are at.
Also, here is a video that shows how to prepare dry yeast: https://www.youtube.com/watch?v=SL92Bd4kfbQ
You do not need to make a starter. If you are brewing a big beer, you can use two packs.
I’ve had a barleywine complete fermentation in about 3 days before, maybe 4. I believe the yeast was a re-pitch from a previous yeast cake so the yeast was super healthy. It can happen if your yeast is really healthy. Take specific gravity measurements several days apart to know if fermentation is truly complete. If it’s still changing then the fermentation needs more time even if you don’t see any activity visually, which is also very possible.
+1 Some yeast slow down a lot as alcohol levels rise. It is not unusual for the last 3rd or so of fermentation to take a long time. Sometimes with really big beers I will use a primary yeast I like and then add an alcohol tolerant yeast like white labs 007, or the sandiego super strain, or belgian high gravity, depending on style after 3 weeks to finish fermentation and dry the beer out if I need/want to.