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Imperial Stout is flat

I brewed some imperial stout and it came out flat and sweet. Could it be that by doing a secondary fermentation I left too much yeast behind?

No that is unlikely the cause. How much priming sugar did you use and what was the highest temperature your fermentation reached. But also how long has it been since you bottled?

I used “fizz drops” at the recommended rate - one per 12 oz bottle. Fermentation was at a pretty constant 68-70 degrees. Fermentation was 3 weeks total - 1 in primary and 2 in secondary. Tried the first bottle at 2 weeks after bottling and the second one two days later.

The bottles are at room temperature still?

I don’t know why but I have found that darker beers have taken a bit longer to reach full carbonation. Give it some more time.

It’s an imperial stout. High ABV beers take longer to carbonate. You just have to be patient and give it more time.


Thanks for all the great advice. The bottles are at room temperature, and I will give them another 2 or three weeks

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With time you may want to customize your sugar to the style of the beer. Imperial Stouts aren’t supposed to be super carbonated.

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IIRC I have not heard positive things about the fizz drops. I’ve heard things from them not fitting into bottles to never fully dissolving.
With that said, this is a big beer with stressed yeast. Likely will need more time. In the mean time flip those bottles a couple times per day to promote the drops to dissolve.
Also, check into our host’s Carbonation calculator . You’ll be able to fine tune your carbonation level with it.


I used those fizz drops they seem to work. I would invert the bottles a few times. They were a tight fit. I wonder if lemon drops would work for certain style

Thanks again for all the good advice, N. Brewer changed their fizz drops a few years ago and the new ones do not fit in the necks of Grolsch bottles, which I use a lot of.

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