before I got 6.5 gal carboys, I used 5 gallon for primary. Downside was massive blowoff, usually would only get 4.5 gal out of the batch due to blowoff. I prefer the 6.5 gal for primary now, I use my 5 gal's for bottling, as secondaries, or for less foamy drinks (mead and apfelwein).
but, with blowoff hose, a 5 gal is fine for primary.
Primary: beer, mead, cider
Drinking: beer, mead, cider
Originally Posted by GilaMinumBeer