Revived Fermentation?

DasBierIstGut · Jun 7, 2014

Hello all, I recently had a batch of brewferm "Diabolo" fermenting. The recipe said to ferment for 10 days then bottle. Well I let it ferment in primary for 10 days, checked the SG, and found it to be unsatisfactory (read 1.020, OG was 1.060). I let it hit the two week mark and checked again to find it exactly the same. So I racked to secondary. Now magically after three days in secondary I have krausen forming and the airlock bubbling again! I'm don't get it, I know that stirring up the yeast settlement could spark up fermentation again, but in secondary? There was no yeast sediment, and I siphoned with minimal disturbance. This is more of a "what's going on?" Question than anything, I'm hoping some of the more knowledgeable have insight, thanks!

flars · Jun 7, 2014

Likely causes of high SG in the primary are under pitching the yeast, poor yeast handling, or lack of wort aeration.
If you used dry yeast did you rehydrate the yeast before pitching? If you used liquid yeast did you make a starter? Did you aerate the wort before pitching?

DasBierIstGut · Jun 7, 2014

Yes, I rehydrated the yeast before pitching, and aerated quite well, I always trickle the wart into the fermenter and stir quite vigorously for maximum aeration, but my question is, what would've caused the fermentation flare up several days into secondary?

flars · Jun 7, 2014

Your wort may have needed more aeration to finish or the temperature of the wort rose in the secondary. Both conditions can reactivate dormant yeast.

DasBierIstGut · Jun 7, 2014

Okay, thanks!

flars · Jun 7, 2014

DasBierIstGut said:
Yes, I rehydrated the yeast before pitching, and aerated quite well, I always trickle the wart into the fermenter and stir quite vigorously for maximum aeration, but my question is, what would've caused the fermentation flare up several days into secondary?

Rather than edit my post;
Don't trickle the wort into the fermentor. Splash it. Don't stir for aeration, shake it violently until you see swirls of bubbles coming up from the bottom.