Airlock active during diacetyl rest?

I brewed a 5 gallon Maibock lager, and had initial very active fermentation with blow-off that subsided on the second day. After 9 days in primary at 50F, the airlock activity had almost stopped. I brought the lager up to 65F for a 2-day diacetyl rest. After nearly a day into the rest I noticed the airlock bubbling away at 10-12 per minute. Is this normal? Should I wait for activity to subside before racking to secondary? Or should I drop back to 50F and wait for fermentation to complete?

 

Remember, and airlock is a valve, a vent to let EXCESS co2 escape...That's all it is.

So what happens to a GAS when it warms up?


It EXPANDS....

Your fermenter was in stasis. The co2 was just sitting there at a certain volume. When you warmed it up, the gas in the container expanded, so much that it is being released out of the airlock.

If folks keep in perspective what an airlock is...a valve, not a "magic fermentation gauge" then folks would worry less if it bubbles or doesn't bubble.

 

I always viewed airlocks as a way for the yeast farts to escape. Or maybe belches.

 

Warmed beer will gas off residual CO2 because of lower solubility. It might not be from fermentation.

 

I believe the main point of a diacetyl rest is to kick the lager yeast into high gear to clean up all of the leftover undesirable flavors. You usually do one right at the end of fermentation so fermentation isn't actually complete yet. Between the gasses warming up and yeast kicking into high gear you'll usually get a jump in airlock activity.

 

This probably should have been mentioned first :thumbs:

 

Nonsense! Yeast Farts come first!

 

I love to watch people's reactions when I tell them "...then I pitch the yeast, they start eating the sugars and start farting a lot..."