Second wort addition formula??

[tahoehomebrewer]

So I brewed up a 5 gallon batch of holiday ale that was a bit lower in original gravity than I was hoping for, 1.054. After allowing the beer to ferment for two weeks I decided to experiment and boiled another 1 gallon of wort, 1.040 OG. This was cooled, aerated and then mixed with the original batch along with some yeast nutrient in a fresh 6 gallon carboy. At this point the original 5 gallons was down to 1.016. Is there a formula for calculating the effect on the gravity with this addition? I'd like to figure out my true ABV when I bottle, but am unsure how to deal with the calculation.

 

[Brooklyn-Brewtality]

Well... I am not sure what you were trying to do by adding the extra wort to a beer that was lower in gravity than you had wanted, because:

Diluting 5 Gallons of 1.054 with 1 Gallon of 1.040 should yield 6 Gallons of 1.052

 

[tahoehomebrewer]

Yeah, it was kind of an experiment. It was a pumpkin ale so there was a lot of trube and I needed to add a gallon when I transfered anyway just to get it back to 5 gallons so I thought that I might as well try to get some more alcohol out of it rather than just diluting it further. Since the original batch had already fermented for two weeks it was down to 1.016 before I added the additional gallon of 1.040 I thought that the additional sugars would raise the alcohol level, but it sounds like your saying it would not since the addition is a lower OG than what the orignal batch started at. So it still ends up diluting it, but it will be less diluted than if I just added plain water. Is that right?

 

[Yuri_Rage]

Your last statement is exactly correct.

 

[eddie]

Yeah, it was kind of an experiment. It was a pumpkin ale so there was a lot of trube and I needed to add a gallon when I transfered anyway just to get it back to 5 gallons so I thought that I might as well try to get some more alcohol out of it rather than just diluting it further. Since the original batch had already fermented for two weeks it was down to 1.016 before I added the additional gallon of 1.040 I thought that the additional sugars would raise the alcohol level, but it sounds like your saying it would not since the addition is a lower OG than what the orignal batch started at. So it still ends up diluting it, but it will be less diluted than if I just added plain water. Is that right?

A better route, IMO, would have been to let the beer develop as it was and make whatever adjustments you needed to the volume on the next batch. Adding the wort to the brew to bring up the volume will result in a change in the malt and alcohol character of the finished beer. What that change is depends on the fermentability, gravity, and volume of the added wort.

 

[tahoehomebrewer]

Right on. Thanks for the info guys. I kind of figured that the yeast would exhibit some more pronounced characteristics after the second addition, hopefully in a complimentary way for the style...but we'll find out in a few weeks. There's just a little bit more hop bitterness than I was shooting for so ideally time and the yeast/malt changes will help balance it out and bring forward the sweeter, spiced flavors, but heck, I really don't know what to expect. As long as it tastes good, right. Any ideas on how to calculate the true ABV on this?

I think perhaps the best advice I've gotten from any source so far is implied by Eddie, brew again!