3 gallon split in a 5 gallon carboy


I am currently doing a split batch of the BB porter. I will be doing 3 gallons standard and doing 2 one gallon batches with additions. Will the 3 gallons be ok in the 5, or is this headspace going to cause oxidation?


You should not notice a problem.

I do three gallon batches in five gallon carboys all the time. As fermentation works it’s lovely magic it will give off CO2 which will force out any concerning level of oxygen. If you’re going to do this I would refrain from opening it a bunch though, I usually just give it the three week window and then take a gravity reading and keg/bottle/rack.

Awesome, thanks guys!