overshot my efficiency by 18 points - How do I calculate top off dilution?

My grain bill was calculated on my normal, shi**y 60%, but I got 78. It was a 3 gallon batch, so now I trying to figure out my ABV if I top off to 4 gallons. I just want to make sure it's not gonna put me lower than 4%

I tried a couple of searches, but this one is about an hour from making it to the carboy.

Thanks for any help!

Here's a pic of the sample. It's Moose Drool clone via Jamil (homebew hefe on left )

Use this calculator from brewheads, seems like it should work. Click Here

I know Beer Smith can do dilution calculations. What was your gravity reading?

Use this calculator from brewheads, seems like it should work. Click Here

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Trying it now! thanks

I know Beer Smith can do dilution calculations. What was your gravity reading?

Click to expand...

1.058 but my target was actually 1.044, not 1.040 like I stated in the subject

Looks like you've got yourself an extra gallon of beer. What did you change in your AG technique, because that's quite a jump.

I went from a mash thickness of 1.5 qts/lb to 2qts /lb. I also reduced my brewhouse losses from 1g to .5g. I'm also using a mash paddle (from the wife) instead of my kid's Fisher Price hockey stick. I think I'll attribute it all to that!

szac said:

1.058 but my target was actually 1.044, not 1.040 like I stated in the subject

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With 3 gallons of 1.058 adding 1 gallon of water will drop you to exactly 1.044.

That seems like a crazy thin mash, but I suppose if you're end product turns out like you want it, then you should keep going with those numbers. I'm guessing that beer will attenuate very well.

I saw the same benefit thinning out the mash on a recent brew, where I also jumped from low 60s to almost 80. I had a full 5 gallon batch, so I ended up with a stronger Helles than I had planned to have. Not that this is a bad thing.

Dilution calculations are pretty easy when you work with everything as "points per gallon". Since you have 58 points and 3 gallons, you have a total of 174 points. Since you want 44 points per gallon, you divide that by 44... giving you 3.95 gallons. Since water is zero points per gallon, you need 0.95 gallons of water to hit your target gravity.

If you took that all in and turned it into a single equation:

Water to add = (Original Volume) *(Original Points - Target Points) / (Target Points)

3 * ( 58 - 44 ) / 44 = 0.95

Water to add = (Original Volume) *(Original Points - Target Points) / (Target Points)

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Thanks! That does make it easier. This is probably the key to helping me figure out my extraction efficiency versus my brewhouse efficiency. I have about of gallon of
'losses' diluting my wort that I never could factor in to my grain bill to hit my targets.