Delayed Gushing During Fermentation

This is my first post here - please forgive me if I chose the wrong section.

I made a pretty standard stout Saturday. Fermentation started by Sunday morning and built up to a good inch and a half krausen. Last night, Tuesday, I checked and the Krausen had started dropping. This evening, four days after the brew, I came back and found that the fermenter had completely gushed through the airlock and all over the floor.

I never opened the fermenter, never even touched it. The temperature raised by about one degree in the room (from 69.2F to 70.1F). All told, I can't think of anything that happened in the meantime.

This is the second time this has happened to a batch of mine. Any idea what happened or how to prevent it?

Thanks -

It sounds like your fermenting a high gravity beer, which usually tends to gusher like this. What you can do is use a blow off tube, or just rig up your airlock by placing one end of a plastic tube over top the air lock hole and the other in a bucket of water. Just make sure the water contains some starsan or something to keep the nasties out of it.

Foam control drops go a long way. I use four drops at the beginning of the boil, and it prevents boilovers and also keeps the kraeusen ring to about an inch up the fermenter.

I use 5-Star Kettle Defoamer 105; Fermcap-S is another popular brand.

I don't think you want to prevent it so much as you want to control the blow-off. Rig up a blow off tube and use it on every batch then you won't have to worry about these things.

Or use foam control as it works pretty darn well.

Mr. Evan:

Very similar to my own experience. Only difference is that my 1.056ish Sierra Clone went off a day earlier than yours. I'm also fermenting at a slightly higher temperature than normal using liquid yeast for the first time. I just stuck a blow off hose into the bung and after a day or so when things calmed down, I replaced the airlock and all is back to normal now.