I normally make 5 gallon wine kits. I purchase a 1 gallon kit and I have 6 gallon fermentor. Will this hurt the wine using the same fermentor? Do I need to get smaller fermentor for small batches?
My initial thought was that you should get a smaller vessel, but thinking it through likely the CO2 would drive out any excess oxygen or the yeast would consume it. I think you should be OK.
I would personally get a second smaller fermenter as it allows you to make a small and a large batch in parallel, which isn't a bad thing :-)