I just joined the AHA a couple days ago and have been brewing 5 gallons batches for some time now. A few friends of mine and I are planning to get together to make a couple 2.5 gallon portions, but my primary concern is will I run into any issues if I ferment 2.5 gallons of wort in a 6 gallon fermenter? Would it be exposed to more oxygen over time? Also, does the fermentation process end sooner for a 2.5 gallon batch than a 5 gallon batch would?
Never did this before, so any help / advice would be appreciated. Thanks.