Carb stone size for Unitank

[fturw]

Hey guys, I have a quick question concerning the sizing of a carb stone
So, every brewery I've worked at has had a brite tank that we tranferred the beer into to carbonate. I'm opening a new brewery and we have bought 3 30BBL Uni-tanks. A couple of brewer friends have recommended transferring into an empty vessel to carb up (basically treating it like a brite tank). I've also heard of other brewers adding the carb stone through the bottom port and carbing that way. I want to use the 2nd method (adding the carb stone to the bottom of the uni-tank). My question is for the people that have experience with this method. What size carb stone should I get (they're all 30 BBL fermenters)? I was thinking of a 12 inch carb stone along with a 12 inch extension tube. Too big, too small, just right?

thank you for looking at my post

[hokus]

We have been running 8" stones with 12" extensions in our 30's, just put them through the sample port if your uni's don't have an additional port for a stone. You can always put a sample valve on the racking arm when needed. We use them both ways, sometimes as a 'brite tank' if we filter that beer or sometimes just run them as uni-tanks. All depends what you want to do.

[fturw]

How long does it usually take you to carbonate 30 BBL?

I'm not going to filter anything