Super active fermentation?

[Dan_K]

Hey guys,
I just brewed my 3rd back of beer, it's BIAB / partial mash, OG was 1.064 and I pitched a 1.5L starter of Wyeast 1318. Beer temp was about 74 when I pitched, cool down to ambient of 71 when fermentation started, about 4-5 hours after I pitched the yeast. Checked it every couple hours, going fine, checked it at 20 hours, going fine. I've been logging the ambient temp and it's been 69-70 degrees the whole time. About 30 hours after I pitched, it just took off. The Kruesan took up all of the void space and beer and yeast started coming up into the airlock. So I pulled the airlock and stopper, rinsed them in Starsan, and then stuck a 1/2 tube on the airlock, put it in a bucket of sanitizer.

Question- why does fermentation take off like this- and what does it mean?

ETA: Checked it again this morning (10 hours later), it's slowed down a little bit and the kreusan is starting to retreat from the stopper.

 

[Erik_Mog]

Plenty of healthy yeast, and they like what they are eating.

 

[kombat]

Ambient of 69-70 means actual beer temperature could have been as high as 80° F. Beer got too warm and yeast became overactive.

 

[Yooper]

Ambient of 69-70 means actual beer temperature could have been as high as 80° F. Beer got too warm and yeast became overactive.

That's what I was thinking. Yeast LOVE warm temperatures. I've personally seen beer be 10 degrees higher than ambient temperatures during active fermentation.

A "stick on" thermometer, like on aquariums, is a quick and easy way to monitor fermentation temperature.

 

[Dan_K]

I'll check it when I get home to see if it's warmer than the ambient temperature.

 

[hellesyeah]

Hey guys,
I just brewed my 3rd back of beer, it's BIAB / partial mash, OG was 1.064 and I pitched a 1.5L starter of Wyeast 1318. Beer temp was about 74 when I pitched, cool down to ambient of 71 when fermentation started, about 4-5 hours after I pitched the yeast. Checked it every couple hours, going fine, checked it at 20 hours, going fine. I've been logging the ambient temp and it's been 69-70 degrees the whole time. About 30 hours after I pitched, it just took off. The Kruesan took up all of the void space and beer and yeast started coming up into the airlock. So I pulled the airlock and stopper, rinsed them in Starsan, and then stuck a 1/2 tube on the airlock, put it in a bucket of sanitizer.

Question- why does fermentation take off like this- and what does it mean?

ETA: Checked it again this morning (10 hours later), it's slowed down a little bit and the kreusan is starting to retreat from the stopper.

Big fermentation!

1/2 blow off on airlock is ideal. Now you know to start off with the BO tube, and I see little reason to shift it back to a reg airlock unless you are bored. The BO tube IS an airlock for sure.

If you have any way to cool the temps down some you'll see less foaming. When I do Hefes known for violent fermentation, I do them at 62F to keep them in check. Unless you have a fridge or freezer with a temp controller, this may present a challenge to you.

Another solution is to use a larger fermentation vessel for beers with a history of big ferm. I use a 7.8G fermenter bucket for a 5.5G batch when doing beers with highly active yeast.