Adding DME to boost efficiency

midfielder5 said:

i don't have it, but if you are misspelling the terms (as in your title) that might be the issue

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ajf said:

Adding DME to your boil will not improve efficiency. It will increase your OG, which could be good if your OG is low. To do this successfully, you need to know your pre-boil volume, post-boil volume, pre-boil gravity, and required post-boil gravity.
Here's the math.
Assume your pre-boil volume is V1, your post boil volume is V2, and your pre-boil gravity is G1.
Your post boil gravity (G2) will be 1 + ((G1 - 1.0) * V1 / V2)
i.e. if you start with G1 = 1.040, V1 = 7 gal, and V2 = 5.5 gal, your post boil gravity (G2) will be:
1 + ((1.040 - 1.0) * 7 / 5.5)
or 1 + ((0.040) * 7 / 5.5)
or 1 + .051
or 1.051

If you want your OG to be 1.062, subtract G2 from that, and that gives you the gravity points shortage. i.e. 1.062 - 0.051 = a shortage of 0.011
Now you need to calculate how much DME you need to add to make up that gravity points shortage.
Assume GS is the gravity points shortage (0.011), and V2 is the estimated post boil volume (5.5 gal)
The amount of DME you need to add is GS * V2 / 0.046 i.e. 0.011 * 5.5 . 0.046 or 1.32 lb DME.

Hope this makes sense,

-a.

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TastySalmon said:

Why not just add more grains to your mash to increase OG? It will save you money.

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sweatje said:

I think his point is he has already mashed out and has low gravity and is trying to correct on the fly. Your approach would work for his next attempt at the same recipe if there were no other process influences though.

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