Pure O2 vs Air

I'm thinking about buying an aeration system. I was wondering: What's better for the yeast? Using pure oxygen from a canister like the ones bought at a local home improvement store or a system that filters ambient air?

Pure O2 works better, faster. Otherwise shaking can accomplish the same as the filtering method.

From memory any method (shaking, fish-tank-air-pump, pouring from height etc) that uses air, has a limit of about 8ppm dissolved O2 - which is adequate for most beer. However, pure oxygen and a diffuser stone allows you to get up to about 23ppm, which is actually most likely too much, but some beers do need more than the 8ppm you can achieve with air alone.

So when you say "too much", does that mean that the yeast will die from too much oxygen?

c0leman22 said:

So when you say "too much", does that mean that the yeast will die from too much oxygen?

Click to expand...

No, but it can affect shelf life of the beer.

c0leman22 said:

So when you say "too much", does that mean that the yeast will die from too much oxygen?

Click to expand...

Yeast will tend to produce more fusel (hot) alcohols if the wort is over-oxygenated.

There's a guy in my brewclub that encountered that very problem in several batches using 3 minutes of pure oxygen (air stone) in a 5 gal batch. He cut back to 1 minute and the problem went away.

I use compressed, dried, sterile air to aerate wort with an SG <= 1.070 and pure oxygen for 1.070+. Works great.

One caveat - this only works with oil-less air compressors unless you have an elaborate air/oil separator...

One of the podcasts, either Basic Brewing or the Sunday Session, did an episode on this and found that the O2 canisters were the best, and the fish pump was the worst for putting air into the wort. Shaking was behind the O2 tank, but quite a bit ahead of the fish pump method. Something about the fish pump just puts a small column of air into the wort and most of it just bubbles out the top before it can be absorbed.

I've been doing some research on the subject lately. Here is my current thinking.

8PPM is fine for most ale yeasts

8PPM is about the limit at room temperature without using O2

Lagers yeasts want 12PPM or more

12PPM can be acheived by shaking/splashing/aquarium pump if the wort is chilled to fermentation temps before aerating.

But hey, I'm still learning.

Fixed that for ya!

arturo7 said:

I've been doing some research on the subject lately. Here is my current thinking.

8PPM is fine for most ale yeasts

8PPM is about the limit at room temperature and ambient pressure without using O2

Lagers yeasts want 12PPM or more

12PPM can be acheived by shaking/splashing/aquarium pump if the wort is chilled to fermentation temps before aerating and/or top pressure is applied.

But hey, I'm still learning.

Click to expand...