Why is it still bubbling?

[Thatsmyleg]

Hi everyone, I wanted to ask about fermentation and why I'm still getting bubbles after - I presume - fermentation has ceased.

I'm using the BIAB method in a Peco boiler, and am letting it ferment in the Peco boiler as well. I've got it sat on top of a small freezer unit while it ferments. The freezer is giving off a small amount of heat at regular intervals. Fermentation seems to last about a week, give or take, at which point bubbling in the airlock will cease. At this point I'm dry-hopping with pellets, put straight into the beer (ie no bag). But soon after adding the pellets it seems that bubbling starts up again, and can carry on for weeks. Any idea why? Is the heat from the freezer causing it? Is it fermentation or is it something else?

 

[Clint]

Fermentation is best measured to decide if it's finished.
Bubbles after adding hops can be c02 being released from solution in the wort...I think!

 

[Banbeer]

If it's still bubbling then it still has enough fermentables for the yeast so keep taking gravity readings to see what is happening, when you add hops it will start to bubble again naturally for a while but not weeks

 

[steveinUS]

Fermentation is best measured to decide if it's finished.
Bubbles after adding hops can be c02 being released from solution in the wort...I think!

Agreed. Adding something dry to a wort that is saturated with dissolved CO2 will provide dry surface areas (“nucleation points”) for the CO2 to come out of solution. (That’s about the only word I actually remember from high school chemistry class.)

 

[Drunkula]

Do a search for "hop creep"

https://allthingsfermented.nz/blogs...ping-techniques-and-how-to-minimise-oxidation
http://beersmith.com/blog/2019/03/31/dry-hop-creep-over-carbonation-and-diacetyl-in-beer/

 

[Thatsmyleg]

Thanks everyone!