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Old 01-24-2013, 04:51 PM   #1
jono1492
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Hey guys, I've brewed a few partial mashes thus far and they all seem to have low ABV. I'm not too fussed, but I would like to know where I'm going wrong and I have a feeling I'm over filling my fermenter, could this cause low ABV and what's a good way to calculate how much to fill my fermenter?

Btw, my last batch was a chocolate stout that only had an OG of 1.032 and finished up at 1.012, and I generally top to 21 litres(5.54gal)

Cheers!

 
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Old 01-24-2013, 04:54 PM   #2
freisste
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Depends on your recipe and your mashing temps. If you didn't hit good temps or stir enough during mashing, you may have lower than expected efficiency.

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Old 01-24-2013, 05:09 PM   #3
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Stirring the mash def helps get the grains evenly soaked. It'll raise your efficiency & thus,your OG. I have plastic fermenters with graduations on them to tell how much to top off to for total recipe volume. I also strain all going into the fermenter to aerate it & get less trub at racking time.
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Old 01-24-2013, 05:14 PM   #4
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Quote:
Originally Posted by jono1492 View Post
Hey guys, I've brewed a few partial mashes thus far and they all seem to have low ABV. I'm not too fussed, but I would like to know where I'm going wrong and I have a feeling I'm over filling my fermenter, could this cause low ABV and what's a good way to calculate how much to fill my fermenter?

Btw, my last batch was a chocolate stout that only had an OG of 1.032 and finished up at 1.012, and I generally top to 21 litres(5.54gal)

Cheers!
Hmmm....that is pretty low. As the other guys have said you should try to increase your efficiency with your grain and you could also keep some extra DME around in case you need to bump up your fermentables.

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Old 01-24-2013, 05:55 PM   #5
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Are you just blindly filling your fermenter up to 5.5 gals, or are you paying attention to your target OG and adding enough water to hit your target? If you are just blindly filling it up to 5.5 gals, then you are probably just watering down your beer. You need to calculate your brewhouse efficiency, and compare it to the brewhouse efficiency of the recipes you are using and adjust your base malt bill accordingly.

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Old 01-24-2013, 06:03 PM   #6
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Quote:
Originally Posted by jono1492 View Post
Btw, my last batch was a chocolate stout that only had an OG of 1.032 and finished up at 1.012, and I generally top to 21 litres(5.54gal)
are you taking readings after you top it up? if so, your readings likely aren't accurate due to the difficulty of mixing water & wort evenly. in the future, take readings before topping and adjust as needed.

 
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Old 01-24-2013, 06:09 PM   #7
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When you do a partial mash, do you also do a partial boil and the top off the fermenter? If so I would expect your OG to be very close to what was predicted but your reading was low due to insufficient mixing of the wort with the top off water.

 
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Old 01-24-2013, 07:53 PM   #8
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Either low mash efficiency or not mixing wort & top off well. And it isn't that hard to mix wort with top off. It just doesn't do it well on it's own. I pour all through a fine mesh strainer in a circular motion so it comes out the bottom of the strainer like rain. Aerates well & helps mix the two. Then I use a plastic paddle to stir roughly for 5 minutes straight. I get accurate readings this way.
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Old 01-24-2013, 07:55 PM   #9
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Quote:
Originally Posted by unionrdr
Either low mash efficiency or not mixing wort & top off well. And it isn't that hard to mix wort with top off. It just doesn't do it well on it's own. I pour all through a fine mesh strainer in a circular motion so it comes out the bottom of the strainer like rain. Aerates well & helps mix the two. Then I use a plastic paddle to stir roughly for 5 minutes straight. I get accurate readings this way.
+1. Never had an issue mixing by stirring, it just doesn't do the work for you like when you add priming sugar.

 
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Old 01-24-2013, 08:08 PM   #10
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That's about it,yeah. You have to work it...
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