Weird Fermentation

[BeerBalls]

I brewed a black IPA last Sunday using a 2L yeast starter, which is what I usually pitch (I tend to brew big beers). Typically I get a vigorous fermentation with very short lag time and I usually get a blowoff. This time I pitched at a cooler temp than usual (I brewed at a friend's house on his rig) and there was a longer lag time, but the airlock got bubbling pretty good by Sunday night. Over the next three days the airlock bubbled steadily (about once every 1 or 2 secs) and never threatened to blowoff. Last night I came home and the airlock was totally clogged and yeasty gunk had seeped out of the carboy around the stopper. It looked like a blowoff, but when I attached a bowoff hose it hardly bubbled (my expereience is that during a blowoff, fermentation is vigorous and a lot of CO2 is being produced). Also, the foam quickly receded. After cleaning up, I reattached the airlock and it continued to bubble about every 4 to 5 seconds. What's going on? Has anyone ever seen this occur - and is it a sign of a contamination? Why would fermentation just move along steadily for days and then suddenly go crazy? I haven't checked on it yet today but am a little anxious to see what shape it's in. I'll post again after I do that.

 

[MalFet]

All fermentation is weird fermentation in my book. You answered your own question, though...cooler temperatures gave you different population dynamics. Everything sounds fine. Bubbles don't tell you much really.

 

[BeerBalls]

I agree about the bubbles - I should've added that a nice krauzen had formed after about 24 hours and fermentation was clearly happening for at least three days prior to the blowoff. I suppose yeast works in mysterious ways...

 

[MalFet]

Yeah, indeed. There's actually a ton of literature about the chemistry of foam. I don't understand any of it, but I know that you can end up with crazy krausen lattices with that only persist in a narrow window of activity. Too much or too little and it collapses. Slight changes in temperature, agitation, etc., can all make weird stuff happen. now the only question is if you like the yeast profile better or worse at this lower temp. Only time will tell