Oxygenation times: batch size, stone type.

I've been oxygenating for a while but new questions have come up because (1) I've switched to ten gallon batches and (2) I recently learned that air stones are not all the same.

First: does the quantity of the batch affect how long one must oxygenate the wort: e.g., if I give 5 gallons one minute with the stone does that mean that to get the same amount of oxygen in a ten gallon batch I must give it two minutes with the stone?

Second: wyeast website says that one minute of oxygen with a stone provides 12ppm. But it does not say what kind of stone. I believe I have a 2 micron (got it from williamsbrew) and my understanding is that between a 2 micron and .5 micron, the 2 micron will require longer times because the bubbles produced are larger. (Incidentally, wyeast doesn't say what size batch one minute will provide 12 ppm to.)

My default procedure (for five gallons) has been to give an average-strength ale a minute with my (2 micron?) stone. But it seems that many may do longer times.

Any advice (especially how long you oxygenate for a given ale or lager) is much appreciated. Thanks.

Just hanging out... Subscribed...thinking about the kit @ Williamsburg also...

I have the Williams wand. Their instructions recommend about 20 - 40 sec of low oxygen output, in other words gradually release the oxygen rather than blast it. Evidently smaller micron stones are better than larger ones as the increased number of air bubbles improves surface area contact with wort.

Jamil Z. essentially recommends the same, however with high gravity wort he recommends aerating for between 1 to 2 minutes. With large barley wines he recommends aerating a second time approx. 12 to 16 hours after initial fermentation begins.

I've been following this advice and its worked well for me.

can you over oxygenate with pure O2 and a stone? or is it just wasteful if you go beyond recommended times?

how funny, another thread on this topic just bumped to the top. In it one poster wrote that for his 11 gallon batch he oxygenated for 9 minutes to achieve 9ppm. That makes me think I have been way under doing it.



"I calibrated the meter to instructions. On my first batch (an IPA) at 74 degrees and an OG of 1.071 and 11 gallons in the conical with a 2 micron stone I got the following readings (each reading was stacked on top of the previous reading, so the 2nd reading is at 6 min and the last at 9 min):

3 min @ 0.5 L/min = 3.5 ppm
3 min @ 1 L/min = 6.4 ppm
3 min @ 1 L/min = 9.2 ppm

So, that works out to 9 min @ .83 L/min for 9.2 ppm at 74 degrees in an 11 gallon batch of 1.071 OG wort."

From: https://www.homebrewtalk.com/f13/aerating-oxygen-129760/index6.html

terrapinj said:

can you over oxygenate with pure O2 and a stone? or is it just wasteful if you go beyond recommended times?

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Don't think you can over oxygenate, but it is wasteful as wort can only hold so much O2.

I can see aerating for 9 minutes with filtered air, but not with pure oxygen.

Here are the instructions that came with the Williams wand:

To Use:

To aerate 5 gallons of wort to 70% of its oxygen holding capacity (a good level for quick yeast growth), sanitize wand and dip into 5 gallons of freshly made cooled wort in a glass or plastic fermenter. Put on safety glasses. Turn on the regulator until you see steady bubbling (not a huge spurt), and keep it going for 25 seconds. Turn off and remove, and your wort is ready for yeast. Aeration becomes more important as the starting gravity of the wort increases.

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My question is not how long to oxygenate five gallons; how long for 10 Gallons? Or more generally, does twice as much wort require twice as much air stone time to absorb an equivalent amount of oxygen.

Sorry If the nature of the question was unclear.

pherball said:

My question is not how long to oxygenate five gallons; how long for 10 Gallons? Or more generally, does twice as much wort require twice as much air stone time to absorb an equivalent amount of oxygen.

Sorry If the nature of the question was unclear.

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I do brew 10 gallon batches, but separate to ferment in 5 gallon carboys. In any case, yes, you'll have to double the O2 injection on a 10 gallon batch to reach same saturation level described above for 5 gallon batches.

According to "Yeast", you can't over oxygenate the wort via shaking/stirring/or air pumps, but you can if you're using pure O2.

I can't remember where I heard/read it, but I think maybe in one of Jamil's podcasts, he talked about someone troubleshooting some taste flaw they'd been getting. He had been using pure O2 for like 5 minutes. JZ recommended backing that time down because it was likely over-oxygenating the wort. Turned out to be the fix.

As for 10 gals vs 5, I wouldn't think it would be twice as long to get the same ppms. Seems like more of the O2 will be absorbed in the larger volume because it has further to travel before it's escapes (and it'll be less saturated overall as it absorbs). Just like if you only place the wand half way down into the solution, you're not going to get as much absorption as if the wand was on the bottom. The further the bubbles have to travel before being wasted, the better absorption rate you're going to have. I figure 10 gallons will need more time, but probably not twice as much.

carrotmalt said:

Seems like more of the O2 will be absorbed in the larger volume because it has further to travel before it's escapes (and it'll be less saturated overall as it absorbs). Just like if you only place the wand half way down into the solution, you're not going to get as much absorption as if the wand was on the bottom.

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This makes sense to me: more. but not twice as much. Thanks. If anyone does ten gallon batches in one fermenter and uses o2, please share your experiences.