I’ve got three 6-gallon glass carboys that I use for primary and secondary fermenting. I rack early after primary, usually within the first three to five days of pitching. There’s about one+ gallon of extra head space above the beer in the carboy, and, though I’m not all paranoid about it, I would prefer to minimize that head space to avoid oxygen in the carboy.
The idea of racking to secondary within a few days is that the yeast are still somewhat active, so they’ll still be pushing out CO2 through the airlock, thereby purging the oxygen out, but it may take a day or so. I’d rather minimize oxygen exposure from the start.
One option is to get a 5-gallon glass carboy, which I will do at some point in the future, but I’ve currently got other equipment higher up in my homebrewing equipment wishlist.
So until I get that 5-gallon carboy for secondary, I’m purging the carboy of oxygen before racking. The basic process is as follows:
You need
- Glass carboy
- CO2 tank with CO2
- A few feet of hosing
How to purge a carboy with CO2
- Hook up the hose to the CO2. Run the other end into the carboy. (I just remove the disconnect from the keg and hose and just use that.)
- Fill up the carboy with CO2 until you feel comfortable with the volume. I open it up for about 10-15 seconds or so.
- Rack your beer on top of that.
Filling a carboy with CO2
As the beer level rises in the carboy, the CO2 will rise with it, and since CO2 is heavier than air, the air will be pushed up and out, leaving mostly CO2 in the head space. The yeast should still be active enough to purge the rest on their own.
Another method is to hold a lighter right above the carboy opening as you’re filling it with CO2. When the flame goes out, then you know there’s no more oxygen coming out of the carboy. (Alex’s idea; thanks Alex!). I’m not bothering with this, since I don’t really want to waste any CO2, as I’ve then gotta drive 15 miles to get it filled up.
How about you?
- Do you purge your carboys of oxygen when racking to secondary?
- Do you use another method?
- Any caveats you see with my method? Or yours?
The post Purge a Carboy with CO2 before Racking to Secondary appeared first on Beer is My Poison.
