so I brewed a American imperial stout on Thursday last week. 1.112 OG with a 2.5 L starter. 6.25 gallons into an 8 gallon fermenter. The thing started fermenting within 2 hours, I mean it took the hell off like an F-16! From the start it was working quite vigorously! I always do blow off tubes first, with how crazy this one was going I put my usual 2 liter container into a 5 gallon bucket to catch overflow if necessary. Glad I did. By Friday morning 1.5 gallons of brew had escaped with the blow off material!!! I've had vigorous fermentations before, but nothing quite as fast and hard as this. That's a lot of brew that got carried out with blow off. Never had more than like .25 gallons blow off before. Anyone had this happen? Trying to figure out what the heck happened...
Holy crap! That is a lot. I have lost .5 gallon before due to blow over. What strain did you use and at what temp?
That sucks that you lost that much beer . It sounds like you just had a really vigorous fermentation, whereas you haven't had that before. As a professional I'd pitch enough fresh yeast that I had vigorous fermentation sometimes within 15 minutes, so perhaps in this case you just 'overpitched' for your set-up.
I was dead on with my pitch rate (I didn't do cell counts or anything too technical) calculations. But, yes I guess it must have been really healthy yeast ready to go to work. I am sad to lose so much brew... I've had crazy fast/vigorous ferments before, but this was ridiculous.
This is fairly common with that high of an OG. When I do really high OG/ABV beers I'll usually split the batch into a couple fermenters to minimize beer loss. For instance. I had 3 gallons of RIS 1.130 OG in a 6gallon carboy. It blew off like crazy and that was 3 gallons of headspace ! Big beers just blow off like crazy.
In my opinion it can be summarized as follows: Lots of food (high gravity) + a 'shit ton' of yeast = big blowoff. I personally make it a point to add Fermcap S to the wort just before pitching the yeast to mitigate the krausen when brewing higher gravity beers. This works for me. I have read where some brewers get the wort on the colder side before pitching their yeast to 'manage' the krausen. Maybe pitching the yeast at something like 64 degrees F would have yielded a less explosive start to fermentation? Cheers!
I think you provided ideal conditions for a yeast orgy -- those little buggers were gorging themselves and procreating at the same time.
I actually did start it off around 62 F and let it ramp up to 67 F. That's typically what I do with big OG beers. Never used fermcap S, so maybe I'll give it a try in the future.
What Jack said – FermCap! I don't know if it'd be able to completely tame that big of a beast, but it would help for sure. It's worked for me in the past, but the highest gravity I've used it in so far was 1.070.
Yeah, I hear ya about big OG beers blowing off big, but I've never had one go this crazy before. I always leave 1.5-2 gallons of head space in the fermenter with my big beers and lose a small amount to blow off. I had 1.75 Gal of head space in this one and I lost 1.5 gallons of brew, wouldn't have thunk it...
The first thing that came to mind for me was how you grab your temp. Did you get a read off the wort, or just go by your controller probe. Next time I bet you'll start a big beer at 56F. Sorry to hear about your loss and I bet you'll enjoy the rest that much more.
