It has become clear that I need to practice my transfer techniques; I just completed a primary-to-secondary transfer which involved what I'm guessing is a fairly significant amount of aeration. During my transfer (1-gallon basic brown beer, direct from carboy to carboy; no intermediate pot), I used an auto-siphon, and ended up pumping oxygen in. In addition, there was air in the line even while the beer was flowing (which I had to restart several times).

Ultimately, if a beer gets aerated, is it a solid bet that the beer will be oxidized and pick up that "musty, cardboard, stale odor and flavor"? Should I not get my hopes up, or might things still work out?


Last night, I opened one of the bottles. Much to my surprise, it was not awful! The carbonation was a little low, it could have had more flavor, and it was a little stale, but it was not the disaster that I was expecting. Hooray!

  • On my second batch I transferred to secondary and left the end of the siphon hose dangling a good 6-8" above the bottom of the carboy, and didn't realize it until I'd transferred about a gallon. I got a fair amount of bubbles, but the brew turned out just fine. So there's hope!
    – TMN
    Jun 5, 2013 at 16:25

3 Answers 3


The bubbles are large so although some oxygen will have been absorbed it's not as much as say sloshing the beer around in the carboy for 60 seconds.

The beer will probably oxidize in time, say 2-4 weeks, but you can do two things to mitigate this:

  1. drink the beer within a couple of weeks
  2. store the beer at fridge temp. This will reduce the rate of staling considerably compared to storing at room temp.

With these measures, the beer should not oxidize much before it's been consumed.

  • It will be a good three weeks at this point; one week in the secondary, 2 weeks to bottle. But I like the takeaway lesson: don't worry, have a homebrew.
    – object88
    Jun 3, 2013 at 16:18
  • 1
    Sorry I wasn't clear - I meant 2-4 weeks after being ready - e.g. 6-8 weeks after brewday. I've had beers oxidize in that timeframe - turn from being very nice, to meh, to brandy/cardboard.
    – mdma
    Jun 3, 2013 at 21:42
  • That should not be difficult to achieve. ;)
    – object88
    Jun 3, 2013 at 23:09

I'd say keep your hopes up. Unless you pumped a ton of air through it, I don't think it will absorb as much as you think it will. The real problem comes when you slosh it around in the carboy afterwards if you are moving it to a fermentation vessel or closet somewhere, since you removed the layer of CO2 that was resting on top of the carboy and replaced it with oxygen. If this is a concern, transfer it where the secondary carboy will be sitting for secondary fermentation, and don't move it, or use a CO2 tank from a kegging system to purge out the oxygen with CO2 before capping it with an airlock and moving it around.

Try a few basic things to keep from oxidyzing during transfer:

  1. Keep the "out" end of the rubber hose submerged in the beer in the secondary carboy until the very end of the transfer has completed. Also, keep it at the bottom of the carboy, so it isn't splashing when beer goes in.
  2. Keep the "in" end of the siphon always submerged in your primary vessel.
  3. With your auto siphon, don't ever use it to transfer hot (as in a boiling or near-boiling) liquid, as it will deform the auto siphon and may ruin the seals necessary to keep air out when transferring (personal experience on this one, my first half-assed attempt at fly-sparging).
  4. Depending on the platforms you are transferring to and from (where your two carboys are at when siphoning), make sure you have more than enough tubing for your siphon. Don't cut yourself short and have to complicate your siphoning process by stacking books under carboys or moving chairs around, just keep it simple and get the right amount plus a foot or two extra, it'll save you a huge amount of hassle.

With experience you'll get better, you just need to try it a few times to get it right. The important ones are steps 1 and 2 above. As long as you keep both ends of the siphon submerged during transfer (past the beginning couple of seconds), there's no way for air to mysteriously get in until the very end, at which point you simply pull either end out and the suction will not pull further air into the wort.

  • The OP said he used an auto siphon.
    – Denny Conn
    Jun 3, 2013 at 15:16

Why would you need to restart the siphon several times? With an auto-siphon, you should have one or two strokes of the wand, and then it siphons until finished.

Also, why are you doing a transfer to secondary at all?

As for air in the line during the transfer, I find if I pinch, rotate and/or constrict the flow near that point where a bubble is present, you can usually "fill it in", and get the bubble to clear.

  • As I mentioned, my siphoning skills are not up to par; the flow stops at some point. Or, at many points. I haven't perfected the process yet. I'm doing a transfer to secondary to clarify and clear out a heavy layer of trub. And yes, I know that doing a secondary isn't really en vogue with homebrewing these days. But that's not really what the question is about.
    – object88
    Jun 2, 2013 at 22:31
  • If you have a siphon of liquid flowing from a source to destination, unless something interrupts it (air gap at the source; line gets plugged; equalization of level) there is no reason for it to stop on its own. You should watch it and find how/why it stops. This will be boring, but what you describe is abnormal.
    – jsled
    Jun 2, 2013 at 23:37
  • Agreed; I completely intend to work out what I'm doing wrong.
    – object88
    Jun 3, 2013 at 6:55
  • I've had trouble with siphoning if there's a lot of disolved co2 in the beer. As the co2 comes out of solution it bubbles to the top of the siphon tube and eventually creates a vapour lock. Jun 3, 2013 at 19:26
  • @object88 everything I have read says that secondary is indeed en vouge, but I am new to this.. would you mind posting a source? I would enjoy reading the argument against secondary. Jun 4, 2013 at 4:45

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