Calculate ABV when adding fermentables in Secondary

[Clint Potts]

Hi,

I've been searching online forums to find a good answer for this question:

I know how to calculate ABV in a routine beer batch. What I can't figure out is what to do with my math if I add additional sugar (honey, agave, etc.) when I transfer to the secondary. If I start at 1.055 and then watch it drop to 1.024 at transfer, but then add 18 oz of Agave syrup. How do I adjust my new starting point? How do I account for the added sugar added midway through the process?

Thank you all in advance.

Clint

 

[JohnSand]

Hi Clint, welcome.
Brewer's Friend has options for other fermentables, including agave syrup. I'm not sure it has an option for adding to secondary, but I don't think it matters, gravity points are the same.

 

[Smellyglove]

I think you can just add them to the OG. As JohnSand said, gravity points are the same.

 

[Clint Potts]

I guess I'm missing how to know the value of 18oz of Agave syrup in 5 gallons of wort. And the batch has already fermented most of the original malt. I bottled the batch on Friday and the final reading was 1.024. This was also the reading of the wort when I added the syrup and the yeast kicked back into 4th gear.

 

[JohnSand]

Which means that all of the syrup fermented.

 

[Clint Potts]

Agreed. But what was the new Original Gravity that the syrup created before falling back to 1.024? And, for discussion, let's use my numbers in the primary. I started at 1.055. It fell to 1.024. For a difference of .031. Then, I add the Agave syrup. It moves up again to something. It ferments this sugar and falls back to 1.024. Using new math, my total drop would be .031 plus the new drop created in the secondary. Right? Let's say that the new sugar added a new .015 to the FG, for a total of .046. That's a big increase of ABV that I'd like to know about.

 

[eric19312]

According to Brewer's Friend calculator 18 oz of Agave Nectar in 5 gallons provides OG of 1.012.
So add 12 to your pre-secondary OG (55) and you end up with adjusted OG of 1.067.
Determine your ABV and attenuation based on OG 1.067.

 

[Clint Potts]

According to Brewer's Friend calculator 18 oz of Agave Nectar in 5 gallons provides OG of 1.012.
So add 12 to your pre-secondary OG (55) and you end up with adjusted OG of 1.067.
Determine your ABV and attenuation based on OG 1.067.

Awesome!! Thank you. That gives me what I was looking for.

 

[eric19312]

Awesome!! Thank you. That gives me what I was looking for.

You are welcome..I was just doing this for a Saison I brewed this weekend that called for a sugar addition after 3 days.