Stuck fermentation?

Carboy fermenter. Image via Wikipedia

Ten days have passed since I brewed a batch of “Hop Grenade,” an IPA. The image on the right is pretty much how my fermenter looks. After ten days, the yeast are still eating. CO2 continues to escape from the airlock. The bubbling isn’t as active as it was seven days ago, still it’s still percolating. The batch tasted pretty darn good. I detected no off-tastes.

This batch’s starting specific gravity was 1.075. It’s now at 1.030.

The recipe for this (coupled with my notes), my second batch Hop Grenade, was:
2-Row Malt, 12lb 0oz, (80.0 % by weight of grain bill)
Caramel 40L Malt, 1lb 0oz, (6.7 % by weight of grain bill)
Carapils Malt, 1lb 0oz, (6.7 % by weight of grain bill)
Corn Sugar, 1lb 0oz (6.7 % by weight of grain bill)

Input 11.0 gallons hot liquor (it’s really hot water but since it’s for making beer and we are particular about the minerals and pH of the water it’s “liquor.”)

66% conversion efficiency expected. Mash (mash is the hot porridge made by combining hot water and the milled grain) at 152F for 60 minutes. No sparge (sparging is rinsing of grain to get all of the sugary goodness).

Output 8.0 gallons wort (raw, unfermented beer)

Wort’s Pre-boil gravity: 1.051

Boil wort for 90 Minute

Hop addition Schedule:

Simcoe 0.80 oz … 60 Min From End
Columbus(Tomahawk) 0.80 oz  … 60 Min From End
Columbus(Tomahawk) 0.20 oz … 30 Min From End
Simcoe 0.20 oz  … 30 Min From End
Simcoe  0.60 oz  … 15 Min From End
Columbus(Tomahawk) 0.60 oz  … 15 Min From End
Amarillo  0.60 oz … 10 Min From End
Simcoe  0.40 oz … 1 Min From End
Amarillo  0.30 oz … Dry-Hopped
Simcoe  0.30 oz … Dry-Hopped
Citra 0.30 oz  … Dry-Hopped

The only thing I have done different from what I have done in the past was to make a yeast starter with White Labs WLP001-California Ale

So, to summarize, I have a batch of beer that indicates the yeast are actively fermenting after 10 days. The specific gravity is 1.030 (starting was 1.075). And, it tastes fine.

Have you had a similar “stuck fermentation” that kept on fermenting? What did you do?


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