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Old 06-29-2011, 04:47 PM   #1
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Default How to adjust for missed preboil gravity

I have Beersmith and I just purchased a refractometer. On my last batch, I missed low on the preboil gravity, and then on the OG. Although, I believe I have confined this issue to a poor crush and low efficiency, I would still like to know how to tweak the boil should this occur down the road. My specific questions are these:

1.) Can I use Beersmith to calculate a DME addition during the boil so that a low preboil gravity might result in an ideal OG gravity? And if so, what is the best way to perform this action within the program?

2.) What is the best practice if the preboil gravity is too HIGH? How should one go about adjusting the boil so a target OG might be achieved?

If Beersmith is not the easiest way to achieve this information, I'm certainly open to other ideas. I'd really like to be able to make adjustments on the fly so the end product is what I set out to make.



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Old 06-29-2011, 05:10 PM   #2
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There is really great chapter on this in 'Designing Great Beers' by Charlie Ray Daniels. Unfortunately, I don't have it in front of me. You can calculate how much DME to add to.raise your pre-boil gravity. I think if it is high, you are stuck with either a stronger beer or diluting to make more beer of the proper gravity.



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Old 06-29-2011, 05:45 PM   #3
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I can do it by hand, but I don't know if/how Beersmith does it.

By hand: Say you have 5 gallons of 1.060 beer and you want it to be 1.050. A gravity of 1.060 is equivalent to 60 gravity points/gallon. First, figure out the total gravity points in your brew. In this example it is 300 gravity points (60 x 5 gallons). To figure our your new volume that you need to have to get 1.050, you divide your total gravity points by your desired gravity points/gallon (in this example you are trying to get it to 50 points/gallon).

So your new volume of 300/50 or 6 gallons. Here you would add an extra gallon of water to your 5 gallons of 1.060 wort to make it 1.050.

Algebraically it follows the V1xC1 =V2xC2 equation.



As for question 2: add water.


Hope this helps...

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Old 06-29-2011, 06:02 PM   #4
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Take the difference between your target gravity and actual gravity and divide it by points per pound of extract. For dme points per pound is 45. For lme it is 38. The answer is how many pounds of extract to add.

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Old 06-29-2011, 10:12 PM   #5
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Quote:
Originally Posted by broadbill View Post
I can do it by hand, but I don't know if/how Beersmith does it.

By hand: Say you have 5 gallons of 1.060 beer and you want it to be 1.050. A gravity of 1.060 is equivalent to 60 gravity points/gallon. First, figure out the total gravity points in your brew. In this example it is 300 gravity points (60 x 5 gallons). To figure our your new volume that you need to have to get 1.050, you divide your total gravity points by your desired gravity points/gallon (in this example you are trying to get it to 50 points/gallon).

So your new volume of 300/50 or 6 gallons. Here you would add an extra gallon of water to your 5 gallons of 1.060 wort to make it 1.050.

Algebraically it follows the V1xC1 =V2xC2 equation.



As for question 2: add water.


Hope this helps...
Question 2 was for how to treat an overshot preboil gravity so what you described would be the solution to #2 right? Calculating how much water to add to thin it down?
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Old 06-29-2011, 10:17 PM   #6
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Quote:
Originally Posted by apparatus View Post
Take the difference between your target gravity and actual gravity and divide it by points per pound of extract. For dme points per pound is 45. For lme it is 38. The answer is how many pounds of extract to add.
Let me run an example past you and tell me if I'm right:

PB gravity = 1.05 measured
Desired PB = 1.06
Gallons in the boil = 6

So (60*6)= 360
and (50*6)= 300

Difference in points is 60

60/45 = 1.33 lbs DME? Is that right?
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Old 06-29-2011, 10:33 PM   #7
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Quote:
Originally Posted by hops2it View Post
Question 2 was for how to treat an overshot preboil gravity so what you described would be the solution to #2 right? Calculating how much water to add to thin it down?
yes
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Old 06-29-2011, 10:34 PM   #8
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Quote:
Originally Posted by hops2it View Post
Let me run an example past you and tell me if I'm right:

PB gravity = 1.05 measured
Desired PB = 1.06
Gallons in the boil = 6

So (60*6)= 360
and (50*6)= 300

Difference in points is 60

60/45 = 1.33 lbs DME? Is that right?
and yes
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Old 06-29-2011, 10:36 PM   #9
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Cool, I finally understand it thanks to you guys.

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Old 06-29-2011, 11:56 PM   #10
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Ok so these guys are putting these number things in my head and I don't like it.



As Ricky would say "What's with all these fancy word papers?"

With beersmith, I would take a pre-boil gravity, plug it into beersmith. If you're in BS2, open your recipe and goto mash details, plug in the pre-boil volume, and the pre-boil gravity. Now you will get a measured mash efficiency. Whoops, it's lower than we guessed? No problem. Go back to the recipe main page, write down or take a mental note of your estimated recipe OG, plug in your (now known) actual efficiency. See what the OG will be now? If it's too low for your liking, add extract to the recipe until you're at the OG that you were expecting.

That's my plan anyways. I did my first AG last weekend and had 3 lbs of DME on hand to compensate. I ended up at a 76% efficiency (I planned for 68-70%!), I was ecstatic.

Good luck!



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