Blowoff??

[Fireman-Mike]

What causes blowoff? I brewed my first batch yesterday, an Irish Red. Been fermenting just over 24 hours. Eearlyer today I found I was having a blowoff. Luckily I caught it very early and quickly fixed up a blowoff tube and everything is fine now. Just wondering what causes a blowoff.

 

[HopsMan]

Very vigorous fermentation without enough head space to accommodate the high krausen. Usually not a bad thing!

 

[Kate00]

Normal fermentation. I use a blowoff tube for every batch, because the little air locks usually don't keep up resulting in a mess.

The blowoff is just from the yeast doing their thing, producing alcohol, CO2 and krausen. Some yeast strains will ferment more vigorously than others resulting in a more violent blowoff. When it slows down you can switch from a tube to a normal airlock if you want. Blowoff tubes are just bigger air locks.

 

[aiptasia]

Yup, we've all been there. Aggressive yeasts going to town on that wort and causing a very high krausen (foaming) while it ferments. This is natural and a good sign that everything is progressing just as it should be.

Next time you visit your LHBS, ask if they have any fermcap. It's usually refrigerated like yeasts and hops, and it's a safe non-toxic anti-foaming agent. Adding a drop or two to your boil can eliminate the foaming during your hot break, and adding one drop per gallon to your wort will keep your krausen to around 1" or so in your fermenter.

 

[Fireman-Mike]

Good to hear. Is it common to have a temp increase during fermentation? My temp has been 66 but is now up around 70. I noticed it shortly after I found the blowoff.

 

[RM-MN]

Good to hear. Is it common to have a temp increase during fermentation? My temp has been 66 but is now up around 70. I noticed it shortly after I found the blowoff.

Yeast give off heat as one of the byproducts of fermentation. The warmer they start (within limits) the faster they eat sugars and the more heat if given off. I like to keep my beer fermenting in a 62 to 64 degree room and have never had a blowoff. The airlock bubbles a bit and that is all.