Hi there - I’m brewing an IPA with Wyeast 1056 American Ale Yeast (optimal 60-72 per the packet) and have my primary in a swamp cooler b/c my apt is too hot, sitting comfortably in the mid 60’s. This morning I went to rotate my ice bottles and noticed the airlock overflowed, even with the temp at 66. I had no bubbles for the first 48 hrs, so it appears the yeast went hyperactive between hrs 48-54? I removed the airlock, re-sanitized it in Star-San, cleaned up the top as well, refilled the airlock with Star-San, and it was bubbling nice and slowly as expected, say once every 10-15 seconds. Going forward I’ll use a blow-off tube and either a bigger carboy or just less volume, but should I be concerned about this? The yeast formed a good seal around the airlock, so I don’t think anything could have gotten into fermentor. Thanks for any assistance.
No worries. With CO2 and krausen pushing out, nothing will get in.
I’ve had it happen so many times I can’t count, nothing to worry about. That said, at 48 hour lag it sounds like you may not have pitched enough yeast.
Thanks for the reassurance. I have a 2nd packet of the Wyeast in my fridge, but from what I’ve read on the boards here is that would be overkill trying to pitch more in?
It won’t do you any good now. Best bet is to make the appropriate size starter (or the appropriate slurry/# of packets/vials) at the beginning. See the pitching calc at www.mrmalty.com to get an idea how much yeast you need to pitch for every batch. But don’t panic about this one. Should be fine. But pitching the appropriate amount of yeast will insure more consistent results.
Brewing TV had an episode talking about open air fermentation. They explained how the krausen provides a protective barrier. So I agree with others, I wouldn’t worry about it. I’ve been thinking of trying an open air hefeweizen myself.
Consider using FermCap-S in the boil and with any yeast starters you make. It keeps the krausen manageable and reduces the headspace requirements. I’ve had a lot fewer messes to clean up since I incorporated it into my brew day.
I have had FEW blow offs when I pitch at lower than optimum temps for the yeast
and let the temp ramp up to ambient. So another variable is to control temp to avoid
blow off. 
I had the exact same thing happen to me. I’ll be bottling/kegging that batch today. This is my accidental side-by-side of a blow-off v. no blow-off. I tasted both batches just prior to dry hopping. The no blow-off batch was more harshly bitter and smelled of yeast farts. The blow-off batch was more pleasant. I don’t no if this difference will survive through packaging, but having the headspace open to the air for a short period of time in the blow-off batch obviously reduced the effects of yeast flatulence. This is making me want to try an open v. closed fermentation side-by-side…