Last night we brewed the dubbel. It’s now 8:15 AM the following morning, and I walk into the brew closet to check on the fermenter.

Looks like we’ve made a mess! So, this is fermentation blow off…

The dubbel is high in fermentable sugars and Belgian yeast is very aggressive. When combined, the primary fermentation period produces a lot of kreuzen. There isn’t enough space in the top of the fermenter to hold it all, so it’s being blown out of the airlock.

Unfortunately, I don’t have the equipment necessary to build a blow off tube for this batch. It didn’t even occur to me that a blow off tube might be needed.

I’ll wipe up as much of the mess as possible and leave this batch as-is. In the future I will try to be aware of which batches are at risk of blow off and be prepared with a blow off tube.

Another lesson under the ol’ brewing belt.