Can I really finish primary in 3 days? Is that possible?

I've been a home brewer now for six or seven years, off and on. Just relocated to San Francisco, upgraded my equipment and brewed a Porter this weekend using a new all grain set-up.

I had a great yeast starter going, fully active, American Ale yeast. I did an iodine test on the wort we pulled from the mash tun before the boil that we read as having good starch conversion. This should be a pretty big beer, started with 11 lbs of grain plus 1 lb each of honey and molasses.

I pitched the yeast at 78 and we had active fermentation within 6-8hrs. By the next morning, the thing was going crazy...I almost got knocked out by the amount of CO2 that had accumulated in the closet where we I keep the primary. Now, by day 3, it looks like its almost completely finished. The temperature is still at about 74, the yeast head is starting to rescind, and I'm getting a huge cumulation of yeast on the bottom of the carboy. Still a bubble every few seconds, but definitely on its way to be finished in the next 12 hrs.

Is this possible? Did I really do it right this time and get primary fermentation in 72 hrs, or did I screw something up? Curious if anyone else has ever been able to achieve fermentation this quickly on a 5 gallon batch.

yeah, it can happen, but don't trick yourself into thinking that it's really all done. there is a lot of follow-up/clean-up work that the yeast need to do after they have finished chewing up the sugar, so let it sit for a while before you do anything with it.

The "active" or visual aspect of fermentation can very easily be done in 3 - 4 days. Especially at those higher temps. But as Walker says, those yeast still have a job to do.

Walker said:

yeah, it can happen, but don't trick yourself into thinking that it's really all done. there is a lot of follow-up/clean-up work that the yeast need to do after they have finished chewing up the sugar, so let it sit for a while before you do anything with it.

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+1. Depends upon your definition of "finished". If a dramatic slowdown in the bubble means "finished" to you, then you've done it in three days. If specific gravity has something to do with your definition of finished, then dust off a hydrometer. And if taste has something to do with what you mean by "finished", then the answer is almost certainly "No. Not yet."

I've had a successful fermentation in 3 days, confirmed with hydrometer reading. My closet was at about 78 also and my yeast was working double time because of the temp. At that temp I always got incredibly fast fermentation. But I still allowed my brews to sit in primary a little longer fir flavor development. Since then I've moved from the humid closet to our basement where it keeps at a nice 68 and the lager fridge is about 44.

Bottom line... if you've been brewing for 6-7years you know to check it with a hydrometer reading before assuming anything, but it is possible!

I'm sure its going to be yummy!

Dude, I hope you have access to a cool closet - yesterday and today were hot as hell in the city. I had my roommates who work at home keep some jugs of frozen water on top of my bucket since my room was close to 80 degrees. The English-style yeast in my beer is really prone to fruity flavors if it gets above, say, 70. I kept it at 64-66, but be careful during the daytime these next few weeks.

Don't. Move. The. Beer.

Even if it dropped a bunch of points in a relatively short amount of time, 3 weeks on the cake yields a much nicer beer than 1 week does. Just my opinion, of course.

I guess with the right yeast, temperature, and wort it's possible. That's not to say that you should rack or bottle after 3 days. There would probably be lots of off-flavors in the beer that the yeast would clean up if given the chance.

Boy, that's pretty warm for that yeast.

With the weather we've been having I'm not surprised, that strain usually finishes for me rather quickly if I've made a starter.

I've had a beer pretty much finish out within 36 hours once. It had even dropped reasonably clear by that point. I didn't check the gravity right then, but I'd be surprised if it wasn't close to my FG (1.056->1.014). I still left that on the cake for a full 2.5-3 weeks, and as others have stated, I'd suggest doing the same.

Especially that warm, you are going to likely have a dry beer with some estery yeast flavors. I hope it all works out for you.

Ya, your beer finished in three days because yeast LOVE 70-75*. They are much more active at that warmer temperature. That doesn't mean they make better beer though. You're going to have lots of fruity estery flavours from fermenting that high. I would definitely leave the beer on the yeast for at least 2 weeks, your beer will be better for it.