Dilution Solution ??

[Peatjam]

Hey there everyone. I just have a bit of a conundrum and I was wondering if anyone has an answer for me:
I brewed a batch of mead a couple of months ago using California Ale Yeast. The volume is about 4 gallons. OG was 1.103, and last time I checked the gravity it had more or less stopped around 1.04. That brings me to around 8.4%. Perfect! That's right around the ceiling that California Ale Yeast can preform. The idea however is to make a "Root Beer" mead. So at bottling time I plan to add 1 gallon of homemade root beer "wort/must" to the batch bringing the total volume to 5 gallons, and the ABV down to 6.7%.
Having said all that I guess my question is: Should I add priming sugar to charge the bottles, or will lowering the ABV slightly allow for a more habitable environment for the yeast, thus allowing them to charge the bottles on leftover sugars from the honey?
I just don't want any exploding bottles.

Thanks!

 

[biochemedic]

So what you're diluting with doesn't have any sugar/honey/fermentables...basically just the root beer flavoring and some volume? If you run the numbers with that assumption, you will drop your gravity to 1.032, and as you've already calculated, you will dilute out your ABV. Anytime you change the environment, your yeast can do unexpected things...yes, fermentation could restart, and yes, with 1.032 left of sugar, you could easily end up with bottle bombs.

The issue is your have 1.032 of highly fermentable simple sugars left over by a yeast that has pooped out, not a beer that has reached attenuation because of left over *unfermentable* sugars/starches/dextrans. Your yeast will not magically know to stop when you have 2.2-2.5 vol CO2 of carbonation (and many not even stop when they again reach 8.4% ABV, of course you will have bottle bombs by that point anyway...) Therefore, you run into the same age old problem...how to make a sweet, carbonated beverage using yeast without causing explosions! Honestly, the best solution is to force carbonate using a kegging system, but if that's not an option for you, you will need to be very careful. A lot of the soda extract manufacturers recommend using screw top PET bottles because the do take pressure better...you only bottle condition for a few days, and then aggressively cold crash, keep the bottles cold, and also want to probably drink them relatively quickly.