Calculating Gravity - Home Brew Forums

 Home Brew Forums > Calculating Gravity

02-04-2009, 06:36 PM   #1
BarrelOfBrew
Recipes

Dec 2008
Trenton
Posts: 9

I am having some trouble finding info on how to do this, and my searches on HBT didn't turn up anything I could use. We are making a batch of semi-sweet grapefruit wine, according to the Jack Keller recipe. I posted in the thread on grapefruit, but I wanted to start a separate thread on this because it's not really about the grapefruit.

We followed the recipe, pitched the yeast, etc., without problems. The recipe calls for adding sugar 2 days into the primary fermentation, which we did, but we foolishly did not take extra gravity measurements before and after adding more sugar.

In a 3 gallon batch, our OG was 1.073, and we added 4 lbs of sugar (two days later). How do I calculate the revised OG?

BoB
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02-04-2009, 07:57 PM   #2
Firstnten
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Oct 2008
Aberdeen NJ
Posts: 378
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Quote:
 Originally Posted by BarrelOfBrew I am having some trouble finding info on how to do this, and my searches on HBT didn't turn up anything I could use. We are making a batch of semi-sweet grapefruit wine, according to the Jack Keller recipe. I posted in the thread on grapefruit, but I wanted to start a separate thread on this because it's not really about the grapefruit. We followed the recipe, pitched the yeast, etc., without problems. The recipe calls for adding sugar 2 days into the primary fermentation, which we did, but we foolishly did not take extra gravity measurements before and after adding more sugar. In a 3 gallon batch, our OG was 1.073, and we added 4 lbs of sugar (two days later). How do I calculate the revised OG? Much thanks in advance, BoB
One pound of sugar dissolved in one U.S. gallon* of water will float the hydrometer to the 1.046.

So lets use some flawed math here. 3 lbs of sugar will raise the SG .046 the extra lb dissolved in 3 gallons of water should raise it and additional .015.

So the total increase should be around .061

02-04-2009, 09:56 PM   #3
Yooper
Ale's What Cures You!

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Jun 2006
UP of Michigan, Winter Texan
Posts: 70,034
Liked 8171 Times on 5696 Posts

I figured 4 pounds of sugar in 3 gallons would raise the SG by 55, so we're close!
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02-05-2009, 03:07 AM   #4
BarrelOfBrew
Recipes

Dec 2008
Trenton
Posts: 9

Thank you! This puts my revised OG at about 1.130 .

The yeast is loving it. Right now the airlock activity is 2-3 bubbles per second.
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02-05-2009, 03:23 AM   #5
Tusch
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Nov 2007
Spring Valley, Ohio
Posts: 1,379
Liked 12 Times on 10 Posts

Yup I can confirm it at 1.130, you're dead on.
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