Should my lager ferment this slowly?

triskelion · Aug 23, 2013

Pitched my yeast a week ago (mangrove jacks bohemian lager), the gravity has gone from 1.038 to 1.033. It's kept at between 10*C and 12*C and I started it at 19*C. I know lager is suppose to ferment slowly, but I was not expecting this. My last IPA went from 1.053 to 1.008 in 4 days! The krausen has steadily been growing and only just about covers the top after a week.

dcp27 · Aug 23, 2013

i havent used the mangrove jack stuff yet, but that does seem very slow. with fermentis lager yeast i'm usually done within a week. you underpitched a bit with only one packet & pitching at high temp doesn't help either, but it should still be moving faster than this

triskelion · Aug 23, 2013

Its only an 11L batch, so I thought my pitching rate would be ok

RCCOLA · Aug 23, 2013

M84 takes a long time to start. Mine wouldn't start fermenting at 50F at all. I raised it to 57F and it took off, held at 55F for fermentation.

I've repitched the harvested slurry twice and both batches started and finished quickly when pitched at 52F.

If it's showing active fermentation now(krausen/airlock activity) it may have just started and may get going well. If not, I'd warm it up to 57F.

triskelion · Aug 24, 2013

There were bubbles and little krausen islands from about day 3. It's just warmed up to 14*C(57*F) and it now has a fully covering krausen. I'm a little worried about stressing the yeast with the temperature going up and down though.

RCCOLA · Aug 24, 2013

triskelion said:
There were bubbles and little krausen islands from about day 3. It's just warmed up to 14*C(57*F) and it now has a fully covering krausen. I'm a little worried about stressing the yeast with the temperature going up and down though.

It's pretty hard to hurt it once it's churning. A few degrees won't matter. I typically will drop my chamber temp to make adjustments during fermentation. Sometimes my chamber ambient is 48-50F with the beer rocking at 52-54F.

Be ready to harvest that yeast when you rack. You'll have a nice amount for your next beer and it will perform much better than the dry-pitched stuff.