Low ABV...Should I Pitch More Yeast?

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brettrae

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Decided to brew a dark mild ale for my 5th home-brew using Safale S-04 dry yeast that I re-hydrated before pitching. My OG was about 1.034, which was lower than the 1.040 the beer recipe indicated it should be. After about 12 hours, it was fermenting happily at a constant 68 degrees (I have it in a mini fridge with temp controller) and there was a thick layer of krausen. I left the house for the 2 days, and by the time I got back, the krausen had fallen back into the beer and it had mostly stopped fermenting. My ferment on the last 4 brews has lasted about a week so I thought this was odd, but I left it alone for another week and a half before the tested the gravity just now. It came in at 1.010 so it obviously did some work, but that gives me a pretty low ABV of 3.2%. It's not supposed to be a high gravity beer, but should I pitch some new yeast or should I just let it sit a little while longer in the primary before kegging? I don't want to overreact but I also don't want watery beer :) Thanks for the help, as always! Cheers.
 
It's going to be a low abv beer, and 1.010 sounds about right for final gravity. You might get down to 1.008 which would be 75% attenuation. I wouldn't worry to much about final gravity. If it tastes good, then that is all that matters.
 
At a couple of weeks its very likely done. You have a low ABV beer primarily because you started with a low OG, not because of a yeast issue. If you want a higher ABV add fermentables.
 
Ok, thanks for easing my anxiety :) Any ideas why I had an OG of 1.034 instead of the 1.040 the beer kit said it should be? Just curious if there was something I should be doing differently next time.
 
Ok, thanks for easing my anxiety :) Any ideas why I had an OG of 1.034 instead of the 1.040 the beer kit said it should be? Just curious if there was something I should be doing differently next time.

All-grain or extract? What was the volume going into the fermenter? Need a little more info to answer your question.
 
Was this an extract kit that used top-up water? If so, as long as you used all the extract and topped up to the correct volume in the fermentor, your OG was actually probably spot on. The reason that you sometimes get a low OG reading in this situation is because the boiled wort and the top-up water stratify in the fermentor, even if you mix them well, and often your gravity reading is drawn from either the weaker or stronger part of the liquid, giving you a low- or high OG reading, respectively. As long as the full amount of extract went in, and the total liquid volume of the batch was correct for the recipe (not higher or lower), then you can count on the actual OG having been 1.040
 
It was a 5 gallon extract kit, and I topped it off with the correct amount of water. Good to know about that....I must have just taken a reading from a weaker part of the liquid. That would also mean that my ABV is actually a little bit higher than I initially thought, if my OG was slightly off. Thank you all for your help....learning more and more each time!
 
It was a 5 gallon extract kit, and I topped it off with the correct amount of water. Good to know about that....I must have just taken a reading from a weaker part of the liquid. That would also mean that my ABV is actually a little bit higher than I initially thought, if my OG was slightly off. Thank you all for your help....learning more and more each time!

Glad we could help!

And yep, your ABV can be adjusted as a result. With that OG of 1.040 and FG of 1.010, you've got yourself ~3.9/4.0% abv, just slightly north of the 3.0-3.8% range given for the style by the BJCP. So technically...a strong mild? LOL :mug:
 
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