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Adding water to post boil wort

Pahlavan

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Hi Guys,

Due to space constraints I am trying to get the most out of my gear.

How can I determine mathematically how much the gravity of wort would change by adding pre-boiled water to a post boiled wort?

For example if I had an 80L pot full of mashed wort and after an hour boil there was, for example, 60L left and the gravity read 1.080, and I then added 20L of boiled water, what would the gravity to be?

Is there a formula for the dilution of gravity?

Also, more complex, if I were to sparge in the extra 20L, could I determine what the extra sugars would contribute?

Many thanks in advance,

Danny 
 
This is easy to do in a spreadsheet or with a stubby pencil. This is also the answer to the kid who sat in the back of Algebra class and whined, "When are we ever gonna' use this stupid stuff!"

diluting with water:
Vol                         60
SG                         1.08
points per liter         80 SG-1, then multiply by 1000. OR: throw away the "1" and move the decimal three places to the right
total points         4800 number of liters times points per liter
water added         20
new vol                 80
new points per liter 60 total points divided by new vol
new SG                 1.06 Points divided by 1000, then add 1


diluting with second runnings:
1st runnings Vol                 60
1st runnings SG                 1.08
1st runnings points per liter 80 SG-1, then multiply by 1000. OR throw away the "1" and move the decimal three places to the right
1st runnings total points         4800 number of liters times points per liter
second runnings vol added         20
second runnings SG                 1.02
second runnings points per liter 20 SG-1, then multiply by 1000. OR: throw away the "1" and move the decimal place three places to the right
1st runnings total points         400 number of liters times points per liter
new total Vol                         80 1st runnings volume plus 2nd runnings volume
new total points                 5200 1st runnings total points plus 2nd runnings total points
new points per liter                 65 new total points divided by new vol
new SG                                 1.065 Points divided by 1000, then add 1
 
Thanks mate,
Thats great
I will have a crack at it and let you know how it goes.

 
Excellent work, durrettd!

This calculation is also available in BeerSmith as the dilution tool.
 
Cool

I have beersmith already. Didn't notice that function. Thanks
 
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