So brewed up a batch of imperial ipa the other day (11 lbs of extract, 2 lbs of grains, and a pound of hops). Threw in two packets of Safale yeast and the next morning it was fermenting hard enough that I switched over to a blow off tube. It was a constant flow of bubbles (about one to two bubbles per second!) for about two days. Now it has slowed to only once every 20-30 seconds. Any ideas why it would drop off so quickly so soon after brewing? Brewed it Tuesday. Could the alcohol have spiked and killed the yeast off? Or perhaps it was just a quick initial fermentation? Open to any ideas and suggestions. We are planning to add a pound or so of corn syrup to it to kick the yeast back in and dry it out a bit, but I don't know if we should do it now or wait... Never run across this situation before. Thanks guys!
Most likely. Sounds pretty normal to me. Assuming your temperature didn't take a nosedive, I'd say it's normal. It wouldn't hurt to add it now. But just so you know... adding fermentables (even 100% fermentable fermentables) won't dry out your beer. You'll still have the same amount of unfermented sugars left over as you would have without adding the sugar. Now if you had taken a recipe and substituted sugar for some of the grain, then that would dry out the beer (as compared to the original recipe).
Take a gravity reading and see how much fermentation has taken place, airlock activity is not a good indicator of fermentation. VikeMan is right about adding the sugar
If you pitch the right amount of yeast, aerate, and control the temps, you should be at or within a couple points of the FG in 3 days. I have seen the fermentation curve of production brewries, and that is the timeline one should shoot for (for ales). Lagers should be done with primary in 5-6 days.
Yeah, when I have a violent fermentation, it doesn't usually taper-off linearly. It normally seems to end be very abruptly. Fermentation/yeast can still be very active even if it doesn't 'look' like it. All sounds pretty normal.
if your fermentation temp was high, it may have fermented faster than usual. how much yeast did you pitch? did you make a big starter?
another thing, aside form bubble counting not being an exact science, what is is that the rate at which bubbles will emerge under the same pressure load for the airlock vs a blowoff tube will not be the same.
