So where will the ABV come out on this one?

[MDB]

I brewed a punkin ale, used the puree, and like many here have said, holy trub loss!! I lost close to 1 gallon when I racked to 2dy (normally I don't but I do find a 2dy gets a little clearer beer and this one needed some serious clearing). Anyway, I was worried about toom much head space and this beer was already higher ABV than I really wanted at 7.8%, the OG was 1.073 the SG at 2dy racking was 1.014, so I added 3 quarts water. How do I calculate the ABV now? I can't begin to figure it out. It is now about 5 gallons, btw.

 

[zeg]

Ok, I'm not checking your math to get the 7.8% here, but if that's correct, and I assume your 5gal is the amount you have *after* diluting with 3 quarts (0.75 gal) water, so you racked 4.25 gal of the 7.8% beer. You start by finding out your volume of alcohol. This was 4.25 gal * 0.078 = 0.33 gal of alcohol. This is now diluted in 5 gal total, so your ABV = 0.33/5 = 6.6%.

 

[ChessRockwell]

You don't have to calculate the abv now with some confusing formula, just take a gravity reading (assuming the water is all mixed in with the beer) and calculate like normal. Although your final abv calculation could be a little off if you lost a lot of liquid with all the trub...

Unless I'm confused!

 

[zeg]

You don't have to calculate the abv now with some confusing formula, just take a gravity reading (assuming the water is all mixed in with the beer) and calculate like normal. Although your final abv calculation could be a little off if you lost a lot of liquid with all the trub...

Unless I'm confused!

You're confused. You can't just measure the gravity and calculate because you've diluted the sugars that were there.

To prove this to yourself, imagine you forgot to add the yeast (and pretend there's no wild yeast). Then you racked and diluted the wort with water. The correct ABV is 0% because nothing has fermented. However, since you've diluted the sugar, the gravity is now lower. Thus, your method would conclude that you have created alcohol merely by adding water to wort.

You can do it your way, but you have to do the same calculation I did, except adjusting your OG measurement to reflect the dilution. It's the same method in essence.

 

[MDB]

Thanks. Zeg your assumptions are correct. And the 7.8 % is not my math, it was beersmith using actual OG and FG. Actually after a day or two what I'm worried about more now is flavor and did I screw it up???

 

[zeg]

Hope it helped. With an OG that high, I can't imagine that an extra 3 quarts of dilution is going to mess up your flavor too badly.