I am thinking about buying a barrel to use strictly for sour beers. I have read about the smaller barrels being problematic due to surface area and oxidation issues. How much of a problem is this? How much of a problem is this with a 15 gal, vs 20 or 50 gal barrel? I like the idea of something in the 15 gal range.
My other question is, if I ended up with a larger barrel--say 30 gal, would I be able to use it to age my sours and only pull 5-10 gall every 6-9 months for bottling, and then top off with a "fresh" batch out of the primary? Basically just drawing off enough to bottle and then allowing the bulk to continue aging.