I usually get 2 2/3 to 2 3/4 cornies of beer per 15 gal batch.
Sankey, how do you get the yeast out of the corny and what do you put it in?
I'm getting 3 cornies that all fill to about an inch or two below where the top rubber handle starts. I'd say that's about a 1/3 or a 1/2 gallon of headspace.
My 3 gal corny is my starter vessel and cropper- the whole circle of life thing.
My process is:
1) I fill it with starter wort and then pressurize it with O2 and shake shake (just easier than using the stone) and then put the spunding valve on it and let the starter absorb O2 under pressure until it starts kicking out it's own (at 2-3psi or what not).
2) Then after cold crashing, I decant in place via a dip tube that only goes down to 3 or 4" from the bottom, leaving the cake. After that I put in the full length liquid dip tube, shake, and push the cake into the primary with CO2.
3a) I can then leave the full length dip tube in and listen to my beer bubble thru the krausen for a while (it's pretty loud in a corny... ping... ping.. ping... hehe..). This is what I'll do if I have to open it up to dry hop. After I dry hop, I move my spunding valve from the corny to the sanke (cause my custom sanke has corny posts on it). Leaving the long dip tube in is just for convenience I guess.
{BTW- This is where I know I got my infection from. Ramping temperature up at the end of fermentation to aid the diacetyl rest produced condensation in the tubing (which I could see) and that was falling back into the fermenter. My beers smelled 'awesome' until right about cold crashing (so, 3 or 4 days after putting the spunding valve on) and they just gradually infected but were completely opaque cloudy. All 3 infections happened in exactly the same way. Beer was drinkable upon cold crashing, but ugly as hell and just not right..}
or alternately
3b) I put a gas dip tube in the liquid side of the corny. That way I never have to depressurize the chain, even to rack. I can push gas into the corny which pushes it into the primary and then pushes finished beer into 3 cornies! Like a gas hopscotch. Anyhoo, my 3 gal corny is sealed up tight with beautiful looking yeast that has nothing but CO2 on top of it.
Since I don't really ranch yeast yet, I do whatever at this point. Usually I will repitch yeast from the cake of the primary. What with all the plate chiller prefiltering I do, my cake yeast is quite pretty too. I only get about 1/2 to 1 vial's amount of yeast from force top cropping, which I'd have to make another starter for if I wanted to just use that. But no doubt it is prettier than the cake yeast and if I did ranch, I'd ranch that yeast instead. That yeast has less hop oils and/or dry hop matter too.
Hope that helps.
P.S. I use a fun tool for decanting my cake yeast, though.... Plastic (see thru) pancake batter dispenser. Yeah baby.