Lager Fermentation Question

My lager has been fermenting for about 3 weeks at about 45-50f. I just brought it in out of the cold to room temperature to warm up before bottling and the airlock started bubbling. No big deal I said, it's just the beer expanding due to the increase in temperature.

A day later and the airlock is bubbling once every 10 seconds or so and the beer is now room temp.

What should I do? Leave it at room temp? Bring it back into the lagering temps?


Thanks!

5 gallons of liquid takes more than an hour or two to warm from 45* to room temp, and as it does more CO2 will slowly come out of solution as well as the beer/air in the headspace expanding. Think about how a bottle of beer or soda will still fizz and be fizzy after it's been sitting out for an hour, now multiply that by a lot.

The yeast may have revived for a bit for a diacetyl rest or maybe are chewing up the last .001 or so of SG, but I doubt fermentation is still active. In any case it won't produce any noticeable off-flavors. Don't worry about it.

It has been a day since it came in. Should I just wait for it to stop bubbling or can I bottle?

If you're not sure fermentation's finished, take a gravity reading today and Thursday to put your mind at ease.

My lager has been fermenting for about 3 weeks at about 45-50f

Click to expand...

Primary or secondary fermenter?
after the primary the diacetyl rest is needed to let the yeast clean up
then lager at 35-40f till the wort clears ( It' worth it)
if you plan to bottle you need to make sure that you have enough yeast to condition.

Yah. Next lager makes sure you actually lager around 35°F. If fermentation is actually done (ensure by obtaining consistent grav readings), and the bubbling is just off-gassing, there's no harm in bottling now. Make sure you use the temperature converters properly, though, in determining how much priming sugar to use, otherwise you'll have some bottle bombs on your hands.