Oxygenating Your Wort and the Importance of Doing So

Oxygen is somewhat of a tricky subject as you need to pay attention to how much you're adding, as well as when you're adding it. Properly oxygenating your wort plays a big role in yeast's ability to reproduce and complete a healthy fermentation. However adding it at the wrong time will either do you no good, or actually do some damage to your beer. Let's go over the topic of wort aeration.

When to Oxygenate Your Wort

Timing is important with oxygen. You need to add oxygen to your wort because a significant amount of it comes out during a vigorous boil, but is important for yeast health and growth during the fermentation.

Adding it during the boil is really doing you no good. It just boils off. Adding it after the yeast is pitched is also a no-no. In fact it can decimate your beer. It will create cardboard off-flavors, and can dramatically cut hop aroma in your beer over a short period of time. Usually if your pale ale loses it's pleasant aroma after just a week or so, some level of oxygenation is to blame.

So the only time you should be oxygenating your wort is after the boil (ideally after cooling) and before the yeast pitch. So now we know when, let's look at a few methods for oxygenating your wort.

Three Ways to Oxygenate Your Wort

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There are three methods to achieving a desirable level of oxygen (8-10ppm) in your wort prior to yeast pitch.  They will all get you to roughly the same place, but require different equipment and levels of effort.

One thing to keep in mind with all methods is, the higher the OG, the more difficult it will be to reach your desired level of dissolved oxygen. Conversely, you'll need more dissolved oxygen for these larger OG batches as you'll be pitching a larger yeast starter. Cooler wort also absorbs oxygen easier, which is another reason you want to oxygenate after cooling.

Siphon Sprayer & Shaking

Oxygenating using a siphon sprayer widget and shaking the wort vigorously will only reach roughly 4ppm of dissolved oxygen in your beer. You technically could reach higher with an extended period of heavy shaking, but it's not typically achievable  unless you're capable of shaking the beer for 5-10 minutes. Now, you may not be able to reach 8-10ppm with this method, but 4ppm is still more helpful than not doing it at all.

Aquarium Pump With Oxygen Stone (Pumping Air)

Oxygenating with regular air and an aquarium pump tops out at 8ppm of dissolved oxygen regardless of the amount of time you leave it running. This however isn't necessarily bad, as that's right at the bottom of our desired 8-10ppm range. You'll want to run the pump for about 15-30 minutes for maximum effect.

oxygenating with aquarium pump

To set this up, you'll need an aquarium pump, which usually comes with tubing. You'll want to cut the tubing and install an in-line HEPA filter along the line. This reduces the chance of contamination. It should go without saying that you'll want to use new tubing, and not the tubing that was submerged in your goldfish's tank recently. Lastly you want to put an air stone on the end of the line which will make the bubbles smaller and absorb better into your beer.

Pure Oxygen  With Stone (Pumping O2)

If you have the setup to oxygenate your wort with pure O2, you're in the best shape of all. Run the oxygen through an air stone at about 1L / Minute for one minute to reach 9ppm of dissolved oxygen in your wort.

With this setup, you run the risk of over-oxygenating the wort, but to do any real damage, you'll need to get to 40 ppm, so unless you leave it on for way too long, you should be fine. One thing to look out for is the amount of foam your beer will make, and it may overflow.

oxygenating pure o2

Oxygenating Your Mead

In beer making you only oxygenate your beer before the yeast pitch, which makes things easier. In mead making, you oxygenate before the pitch, and again a couple days into the fermentation. You also want to remove the CO2 in solution by degassing along the way.

Before the yeast pitch in mead, you would follow a similar regiment to what you did in your beer. Remember though that the OG of a typical mead is above 1.100, so you'll need to work a little harder to get the oxygen in there.

After a day or two of fermentation, you'll want to open the lid / remove the bung, and degas your mead. A few methods include shaking, using a paint stirrer on a drill, or other similar method. It will have the same effect as shaking a soda. Lots of bubbles (again watch out for overflow). Continue until the bubbles stop forming (this may take a lot of shaking, but less time with the latter methods). Then charge your mead with oxygen one last time. Don't forget to stagger your nutrients too!

Oxygenating your wort or mead must is an important step in making great beer and mead. Check out Home Brew Supply's aeration supplies and aquarium pump kit, which comes with everything you need to aerate your beer up to 8ppm.

by David Doucette
David is a full blown fermentation enthusiast who has dedicated much of his free time to learning and sharing the art of homebrewing. He's spent several years documenting and writing homebrewing information on his blog Hive Mind Mead. He's written over 60 articles between Homebrew Talk and Homebrew Supply.
written by David Doucette

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8 comments on “Oxygenating Your Wort and the Importance of Doing So”

  • Charlie Papazian advises oxygenation immediately after pitching your yeast.
    This has been my practice for over 6 years w/ very good outcomes.
    I use a stone & medical grade 02

    Reply
  • been grain brewing for 20 + yrs..NEVER did more then shake my fermentor a little after pitching in my yeast.... all of the above is a waste of time and money..... relax don't worry.... have a home brew...

    Reply
  • Brilliant information. I had already bought a pump with tubing , stone and air filter but now realize that I also have the extra option of using my wife's Oxygen Concentrator machine instead of the supplied air pump. These machines are cheap to buy as used and are able to provide 95% pure O2.

    Reply
  • I have a cheap used Oxygen Concentrator that produces 95% pure Oxygen that I can use to push O2 through the air stone that I recently bought, instead of its air pump.

    Reply
  • Wannabe beermister October 16, 2016 at 10:49 am

    Using the aquarium pump method is there a formula for how long to airate based on the size of the batch (5 gal, 15 gal...)?
    Thanks

    Reply
  • Steve in orlando October 19, 2016 at 11:46 am

    Would an air pump, like for filling an air mattress, work the same way? Any guess how long to run the pump?

    Reply
  • I gave up all the hard labor a couple years ago for a drop of olive oil instead. Beers are fermenting out great!

    Reply
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