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Old 11-09-2007, 08:16 PM   #1
gallagherman
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Default Gravity readings account for water loss?

To ultimately end up with 5 gallons of beer I bump up the wort to 5.25ish gallons when I pitch the yeast because I have been losing a few inches of water during fermentation. I thought about it and noticed that this is diluting all the sugars in the wort, and my OG will be lower than if it were only in 5 gallons. So... the OG is for 5.25 and after fermentation the FG will be for 5 gallons. When calculating the ABV won't the actual % be higher than what I calculate because the OG is falsely low? Does anyone know that the heck i'm talking about?

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Old 11-09-2007, 08:38 PM   #2
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Alcohol has a lower gravity than water so you ABV will be apparent rather than real.
You can calculate Real from apparent.

Is that what you mean.

The Volume of a brew will not affect the ABV.
If you are saying you are loosing water by evaporation then I should imagine the alcohol is also evaporating.

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Old 11-09-2007, 08:41 PM   #3
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Quote:
Originally Posted by gallagherman
To ultimately end up with 5 gallons of beer I bump up the wort to 5.25ish gallons when I pitch the yeast because I have been losing a few inches of water during fermentation. I thought about it and noticed that this is diluting all the sugars in the wort, and my OG will be lower than if it were only in 5 gallons. So... the OG is for 5.25 and after fermentation the FG will be for 5 gallons. When calculating the ABV won't the actual % be higher than what I calculate because the OG is falsely low? Does anyone know that the heck i'm talking about?
The gravity reading is not dependent upon volume. You aren't losing water, sediment is dropping out, you are losing some sediment and beer.
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Old 11-09-2007, 10:32 PM   #4
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and by adding water, you are NOT falsely changing the gravity, you are actually changing it...lowering it a little, because water has a lower gravity than wort.

adding water dilutes gravity, boiling to cause evaporation increases gravity since only h20 evaporates.

it is normal to shoot for 5.25 gallons to accomodate the loss during racking, but its easier to do that in All Grain brewing since you're not stuck with set quantities of DME or LME (or rather, its easier to tailor a recipe to give you 5.5gallons into the fermentor by adding a smidge more grain and water)

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