I have been brewing all grain BIAB for about a year. I make 5 gal batches and usually keg my beer, but I like to bottle about 2 gal from the keg. I would like to step up to a 7.5 gal batch which would allow me to bottle 2.5gal and still have a full keg. My questions is how do I ferment this? I have 2 6 gal and 2 5 gal carboys. Should I split the batch equally in 2 carboys? Can I secondary in a 5 gal carboy, or I do I need to get a 3 gal carboy and split the batch into a 5 gal and 3 gal for secondary fermentation? I do have one 2.5gal keg also.