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Forgot to top off batch, worried about unfermented sugars

Hello All,

I am brewing my first batch of beer right now. I used the partial mash version of the following recipe (A Yeti Imperial Stout clone):

[quote]Great Divide Yeti Imperial Stout Clone

5 gallon/19 L, partial mash; O.G. = 1.090; F.G. = 1.018; IBU = 75 SRM = 98; ABV = 9.3%


9 lbs light LME
2 lbs (6.9 kg) American 2-row malt
1.0 lb (0.45 kg) crystal malt (120 °L)
12 oz. (0.34 kg) chocolate malt
12 oz. (0.34 kg) black patent malt
10 oz. (0.28 kg) roasted barley
8.0 oz. (0.23 kg) flaked wheat
8.0 oz. (0.23 kg) flaked rye
14.3 AAU Chinook hops (60 min) (1.1 oz./31 g of 13% alpha acids)
7.2 AAU Chinook hops (30 min) (0.55 oz./16 g of 13% alpha acids)
5.3 AAU Centennial hops (15 min) (0.50 oz./14 g of 10.5% alpha acids)
0.5 oz. (14 g) Centennial hops (5 min)
Wyeast 1056 (American Ale) or White Labs WLP001 (California Ale) yeast (3 qt./~3 L yeast starter)
0.75 cups corn sugar (for priming)

Step by Step:

Mash at 150 °F (66 °C). Boil for 60 minutes, adding hops as indicated above. Ferment at 70 °F (21 °C).

Step by Step:

Heat 2.3 gallons (8.7 L) of water to 161 °F (72 °C). Submerge grain bag(s) and partial mash at
150 °F (66 °C) for 30–45 minutes. (Note: this is just over 6 lbs. (~ 3 kg) of grains, you may need more than one grain bag, depending on size. Putting your brewpot in your oven on its lowest heat setting may help you maintain partial mash temperature.)

Remove grains, rinse grain bag(s) slowly with 1.0 gallon (3.8 L) of water at 170 °F (77 °C). Add water to brewpot to make 4.0 gallons (15 L) of wort; stir in roughly two-thirds of the malt extract. Bring to a boil. Boil for 60 minutes, adding hops at the times indicated in the ingredient list. Add remaining malt extract with 15 minutes left in boil. Cool wort, transfer to fermenter, top up to 5
gallons (19 L), aerate and pitch yeast. Ferment at 70 °F (21 °C).[/quote]

I made one big mistake in this recipe, and that is that I forgot to top the batch off to 5 gallons after the boil, as indicated. The beer fermented pretty ferociously for the first 4 days or so, then by a week, it was making no noise at all. At that point, I transferred it to a glass carboy (another mistake, most likely). I took a hydrometer reading of the cooled wort before fermentation and it was right around 1.11. My most recent reading after 3 weeks aging in the secondary carboy was 1.034. My concern is that I’ve left too much fermentable sugar in the beer, and I plan on bottle conditioning the beer, so I’m worried about bottle bombs.

Am I OK to bottle this beer as is, or should I try to pitch more yeast? The beer tastes pretty good so far, and I’m fine with it being higher ABV than initially intended, I just don’t want bottles to explode. Any advice?

You should have left this beer on the yeast for at least a month, if not longer. All is not lost though. Beers this big take a while to ferment all the way out. There might not be enough yeast to finish it, time will tell. The only way to tell if it is done fermenting is to wait for a week or 2 then start taking gravity readings a couple days apart, when you get the same reading a couple checkings in a row, You’re there. Maybe finish in the 1.02’s. If it doesn’t fall that far, you might have to re-yeast, but I’d let that dude sit for a while before I did anything to it.

Good luck!!


Thanks for the advice!

You’ve got an apparent attenuation of 70%, which is pretty typical of complete fermentation for extract recipes. But you’ve also got an ABV of 10.2%, which is pretty close to the limit for what most ale yeasts can achieve. I would agree that you should leave it for a week or two longer to make sure the FG is stable, but I’d be more worried about the yeast being at the alcohol tolerance limit and not being able to carbonate the beer than I would that you’ll have bottle bombs.

Is there a stronger yeast I can use for bottling? I’ve read a few times to use champagne yeast.

Pretty much any wine yeast will work - if you prep them for entering an alcoholic environment. I’d recommend EC-1118 or K1-1116 as the best for this, as they will likely take off strong simply by hydrating them in water for 20 minutes before pitching.

Dilute at bottling. Here is an excellent resource to guide you:

Use distilled water from an unopened jug. It will be sterile so you won’t need to boil and cool it before use, and because you’re bottling the dissolved oxygen in the water is not an issue; the yeast will consume it during the bottle conditioning phase.

Thanks for your replies, everyone. I think I’ll take another reading this weekend. If it’s still stuck at 1.034, I’ll repitch with wine yeast, and then I’ll probably still thin it back out with distilled water at bottling (unless anyone thinks there’s a problem with doing both of these things). Thanks again!

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