This is definitely a noob question, so I thought I would put it out there.
I am soon to be in a situation where I will have enough ingredients to brew two batches of beer the same weekend! (Not a terrible problem to have, by the way).
My problem now is that I have only one 6.5 gallon carboy, and two 5-gallon batches of beer that I want to make. I also have two 5-gallon carboys that I typically use for secondaries, but no fermenting bucket or any other suitable containers for a 5 gallon batch. The two styles of beer I'm making are a Honey Nut Brown ale and a California Common - both with estimated OGs around 1.060.
My question is this: can I put 5 gallons of the California Common beer in the 5-gallon carboy for this beer's primary fermentation? This would be my first time using the bottom-fermenting California lager yeast strain, so my reasoning is that since the yeast will primarily chill at the bottom, an ale-like kraeusen wouldn't be forming - thus not as much headspace would be needed, and a 5-gallon carboy might do the trick.
Other solutions to my problem that spring to mind are: A: split one of the beers 2.5/2.5 into each of my two 5 gallon carboys and carry out primary fermentation separately, or B: attach a blowoff hose to the 5-gallon primary fermentation undergoing California Common.
Of course option C always exists: brew and ferment them one at a time in the 6.5 gallon carboy. But that's no fun, and I don't want my milled grain to get stale
Any thoughts? I feel like I'm making things needlessly complicated again, and probably answered my own question somewhere in this massive wall of text. Thanks!