Novice question about secondaries

Depends on your bung material. If you use a silicone bung you'll actually have more O2 permeation than an air-lock. The 3-piece air-locks and rubber bung have the least amount of permeation without using a BB dry-tap air-lock.

Personally, I'd just switch out the blow-off with a 3-piece and be done, but the S air-locks require less topping up.

 

I use a 3-piece airlock on everything, even the sour barrel that secondaries for years. I make a point of looking at everything at least once per month, and that shouldn't be too much trouble.

 

If I started with one, yes, I would switch to the airlock, mostly because it would take up much less space and use less star san in the airlock. But I am talking about something going for months to years.

 

I have been happy with airlocks to condition Flanders Red, lambic style ale, and a couple of more original American sours. If anything, my process is slow to develop acidity. Even a 3 year straight lambic in a 10 gallon barrel did not become vinegar or get too sour at all. Temperature plays a role, too, I'm sure, and my long term conditioning is in my basement, with cool, consistent temperatures.