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Old 06-17-2011, 12:36 AM   #1
May 2011
Green Hills, PA
Posts: 24

First, I'm sorry if this one has been asked a lot. My search didn't get me the answers I was looking for.

I am making both a cherry stout, and a peanut butter stout. Brewed and fermented a 5 gallon base stout (extract kit) in the primary. This was then split in half as best I could into 2 carboys. The OG after the batch was topped off to 5 gallons (partial boil) was 1.060. After just over 2 weeks in primary, my hydrometer reading was 1.022. Now for some details:

Carboy #1- cherry stout.
Racked approx 2.5 gal on top of 6lbs of Vinters Harvest cherry puree. Yes I know that's a lot, but I wanted a strong cherry flavor. The can of puree lists a specific gravity of 1.092-1.115. Total sugar added was 380g. There is some other info as well for wine making I think. If any more info is needed, I can provide that as also. Should be noted that this carboy got a little bit more beer racked in than the other one. I went by the graduations on the bucket minus a "best guess" to account for trub in the bottom of the bucket.

Carboy #2- Peanut butter stout.
Racked slightly less than 2.5 gal on top of 3 jars of Bell Plantation PB2 powder mixed into 6 cups (64oz) of water. I mixed the powder with water that was boiled right after being removed from heat for sanitization purposes. I did not add this to my main boil because I'm trying something different. The PB2 solution was cooled to room temp prior to racking. Now, each jar contains 6.5 oz of powder totaling 15 grams of sugar, or 45 grams for all three jars. No specific gravity was listed for these.

So to sum it up:
OG - 1.060
Gravity after 2.5 weeks in primary- 1.022

1st carboy: Approx 2.5 gal on top of 6lb cherry puree.
SG listed on each can of puree- 1.092-1.115 (two 3lb cans used)
sugar in each can- 190 grams for a total of 380 grams

2and carboy: Approx 2.5 gal on top of 45 oz PB2 powder mixed with 64 oz or 1/2 gal (pre boil volume) of boiled water to form peanut butter paste.
Sugars- 45 grams total for the three jars.

So, can anyone tell me how this will affect my gravity in each carboy? I'm assuming I need to add something to my SG reading taken after the primary? Not sure how to proceed, so any help on this is much appreciated. I know some of the non exact volumes may affect accuracy here, so I'm not too worried about that right now. Just looking to get a general idea.

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Old 11-18-2011, 04:38 PM   #2
Sep 2011
Prescott, AZ
Posts: 2
Liked 1 Times on 1 Posts

If you know the SG of any secondary fermentables (fruit, juice, etc) and its volume, you can adjust your OG to reflect the addition with a simple formula:
C1V1+C2V2=CtVt, where C is concentration (in SG), V is volume, 1 is your primary fermentation, 2 is your secondary, and t is the total value. For example, I recently added .5 gal of 1.088 prickly pear juice to a fermented batch of blonde ale that had started as 5 gal of 1.050 wort. To determine the adjusted total OG, the formula would look like this: (1.050x5)+(1.088x0.5)=5.5Ct. Solving for Ct you end up with an adjusted OG of 1.060.

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