Using a 20 BBL Bright Tank for 10 BBL Batches

[KRB2012_]

We are just about to place our equipment order for a new 10 BBL brewhouse and fermentation tanks. We're looking to go with 3-4 fermenters with 1 bright tank. At least one of the fermenters will be a 20 BBL. It seems like the most efficient thing to do would be to size the bright tank at 20 BBL as well, but we're concerned about using the 20 BBL to carbonate our 10 BBL batches. That seems inefficient. We'd be wasting quite a bit of CO2 and we'b be putting more 10 BBL batches through the bright than we would 20 BBL batches. However, pushing the 20 BBL batches through a 10 BBL bright in two stages is fairly inefficient as well. Any suggestions on the best way to go here?

[CopperKettle]

CO2 is cheap in the long run. It's either extra cost from CO2 or labor with your setup, as you hinted at. If you have a tap room to make up some margin you won't even notice the extra cost. If you are pure wholesale you may need to add $1-2 to the COGS of an average keg but it shouldn't be much more than that.

We half fill BBTs quite often. My recommendation is to start carbing with 6-8 psi head pressure in the tank instead of 0-1psi so the extra gas you would regularly have to run through the carb stone to fill that head space void with pressure doesn't affect the carbonation. Once you get the tank up to 12-13 psi at 34-35F you will be good to go to package into kegs/bottles/cans. Once you reach your target PSI leave the tank closed to CO2 entirely for 2-3 days and watch the pressure. If it goes down you either have a leak or are under carbed.