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Brewing Topics => All Grain/Advanced => Topic started by: markok on November 21, 2012, 07:26:16 AM

Title: calculating DME addition to bring up wort points
Post by: markok on November 21, 2012, 07:26:16 AM
Does anyone know if B.S. can calculate how much DME to add to post mash if efficiency is off. Let's say I'm looking for a pre-boil gravity of 1068 and it's only 1058. This would apply to a 5 gal batch with no top off water (all water gotten from sparge)
Title: Re: calculating DME addition to bring up wort points
Post by: GoodisBeer on November 21, 2012, 04:42:21 PM
I'm not sitting in front of BS, so I cannot answer that at this time. However BS Lite for Android doesn't have such a tool; it should and I will forward the suggestion. 
Yet I have used an Android App in the past that will make the gravity correction for you, Brewzor Pro, but you need to know the pre- boil volume. I did some calculations for you based on some assumed volumes.
Your preboil gravity of 1058 with desired gravity of 1068:
5 g add 18.18 oz (1.10lb) of DME
6.5g add 23.64 oz (1.51 lb) of DME
8.49 g (this is my usual pre-boil volume based on loss) add 30.76oz(1.91lb)I've of DME.

I've seen the calculation in Palmer's How To Brew as well, but again don't have it in front of me.

Hope that helps. Download the app or give.me your volume and I'll plug it in for you.
Title: Re: calculating DME addition to bring up wort points
Post by: merfizle on November 21, 2012, 05:45:43 PM
It does not...I created a note to help me with that.  Here's the formula using my old setup as an example.

This assumes that your typical DME has 44 points of potential yield. 

n=number of gravity points to raise
v=current wort volume
w=lbs of DME needed to raise wort (n) gravity points

w = n * (1 / (44/v))

Example:  Let's say current wort volume is 7.5 gallons.  Current gravity is 1.048 and you want to increase to 1.052.  So,
v= 7.5 gallons
n = 52 - 48 = 4

w = 4 * (1/(44/7.5))
   =  4 * (1/5.87)
   = 4 * .17
    =  .68 lbs or 308 grams

I hope this helps.

Mark

Title: Re: calculating DME addition to bring up wort points
Post by: markok on November 22, 2012, 08:03:35 AM
Thanks guys. I appreciate you taking the time to help me out here. Could you also take the SG of the particular LME or DME and divide it by the number of gallons. Say for instance you had an LME that was 1036. For a 6 gallon preboil you would have 36/6 or 6 points added per pound of LME. Therefore to raise the gravity by 5 points you would add 1lbs * 5points / 6 points per pound or 13 oz.
Title: Re: calculating DME addition to bring up wort points
Post by: merfizle on November 22, 2012, 06:37:04 PM
That's correct. 
Title: Re: calculating DME addition to bring up wort points
Post by: grathan on November 24, 2012, 10:37:12 AM
that all seems complicated. Could one just put dme in the recipe after putting the low preboil OG numbers in and watch the numbers change based on the amount of dme entered?
Title: Re: calculating DME addition to bring up wort points
Post by: GoodisBeer on November 24, 2012, 02:18:28 PM
Done that too grathan
Title: Re: calculating DME addition to bring up wort points
Post by: tom_hampton on November 24, 2012, 08:58:56 PM
During the brew day I always work in total points. My goal is a certain number of points in the kettle.  I find that easier on the fly.