Author Topic: Formula to calculate Oxygen additions?  (Read 1226 times)

Offline laserghost

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Formula to calculate Oxygen additions?
« on: September 04, 2018, 12:45:51 PM »
I haven't brewed in a while and am revving up for a brew day. One of the things I needed to refresh my memory on was how long I was running my pure 02 tank (through a .5 micron stone) to oxygenate the wort before pitching. I have a medical regulator on the tank and can control the flow down to .12 liters/minute. Historically, I think I'd run it at 1 liter/minute for 60 seconds for 5.5 gallons of 1.060 wort, and run it a little longer if it was a bigger beer, but it was mostly guess work, though the results were always good.

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Re-reading Chris White and Jamil's book, YEAST (pp 77–84, "How Much Oxygen Is Needed?") it states that for 5.3 gal of 1.077 wort, you would run oxygen at 1 lpm for 1 minute through a .5 micron stone to reach an ideal ~9.2 ppm dissolved oxygen. For higher gravity beers, or larger batches you would need to use more yeast, and therefore more oxygen.

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I was playing around to come up with a formula to accurately oxygenate a batch of wort based on volume and gravity, but I'm not really sure if this is solid or not. Maybe the actuals are not quite so linear? Any feedback is appreciated!

(this is assuming pure O2 run through a .5 micron stone at 1 lpm to reach ~9.2 ppm dissolved O2)

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FORMULA

(volume in gallons · gravity points) / 6.8 = time in seconds

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EXAMPLES

(5.3 · 77) / 6.8 = 60s

(5.3 · 57) / 6.8 = 44s

(15 · 67) / 6.8 = 148s

(.75 · 80) / 6.8 = 9s

yeast starter (.5 · 37) / 6.8 = 3s

————

Thoughts?


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Offline klickitat jim

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Re: Formula to calculate Oxygen additions?
« Reply #1 on: September 04, 2018, 01:04:08 PM »
We seek perfection. But I think this is one of those areas where getting close enough is way good enough. There's a few areas of overlap too. And some things that effect the targeted perfection. Like wort temp related to ability to hold dissolved O2.

If you have an active yeast pitch, wort chilled to pitching temp, and a minute of oxygen... you are going to be so close to a perfect situation that any improvement would not be noticed.

If you are seeking an exact targeted DO in your wort, you will need a DO meter. I wouldn't sweat it

Offline Robert

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Re: Formula to calculate Oxygen additions?
« Reply #2 on: September 04, 2018, 01:38:52 PM »
1 lpm may be too much flow also.  If you see bubbles breaking the surface, then they aren't dissolving, and you're wasting oxygen.  It is also very easy to over-oxygenate with pure O2, if in fact it is all dissolving.   In fact, in pitching wort, I've gone back to using 5 minutes of sterile filtered air with an aquarium pump and a 2 micron stone, with improved results over pure oxygen (though I still sometimes use O2 and a 0.5 micron stone for propagation.)  This will get you "close enough" as Jim says without added risk.  Again, to avoid the risk of overdoing it, you'd need a DO meter.  Save money and RDWHAHB.
Rob Stein
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Offline laserghost

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Re: Formula to calculate Oxygen additions?
« Reply #3 on: September 04, 2018, 02:04:28 PM »
Thanks for the opinions guys! Since I already have the O2 tank and setup, I don't see myself ditching it to get an aquarium pump setup. My O2 tank is a decent size welding tank. I've filled it once and the regulator still shows it's full after lots of brew days. I'm not worried about the expense of the O2! According to the book, with an aquarium pump you can only hope to get at best 8ppm DO, which is the minimum of the recommended 8–10ppm, even with extended aeration (which can be detrimental to head formation and retention, according to White).

Probably good enough to make a good beer though!

Robert, you say it's easy to over-oxygenate with pure O2 – that's the reason behind this formula idea – to dial it in based on the particulars of the wort. But, according to the book, 60 seconds at 1 lpm for 5.3 gal of 1.077 is going to result in the optimal ~ 9.2 ppm DO. If I were to run it for a minute on that wort, and some of the O2 were to bubble out, then I'd assume I'm under 9.2 ppm.

I can dial the flow back to .12 lpm and increase the time x8, or set it to .2 and increase the time x4 – I can get it to flow so that it's not bubbling out of solution. That's what got me wondering about how long to run it, depending on the flow rate, and the characteristics of the wort. I primarily do ales and oxygenate at pitching temps, so temperature is typically ~65–70 when adding O2.

I realize this might be overkill, but for the sake of getting in the ballpark and not over or under oxygenating the wort, I'd love for someone to be able say whether this formula has legs or not.
« Last Edit: September 04, 2018, 02:09:09 PM by laserghost »

Offline Robert

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Re: Formula to calculate Oxygen additions?
« Reply #4 on: September 04, 2018, 02:17:09 PM »
With a good pitch of healthy yeast, you likely don't even need the 8ppm.  Err on the side of under. Check out this recent thread:  https://www.homebrewersassociation.org/forum/index.php?topic=32155.0
Rob Stein
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Offline laserghost

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Re: Formula to calculate Oxygen additions?
« Reply #5 on: September 04, 2018, 07:52:03 PM »
With a good pitch of healthy yeast, you likely don't even need the 8ppm.  Err on the side of under. Check out this recent thread:  https://www.homebrewersassociation.org/forum/index.php?topic=32155.0

What is this based on though? The Chris White and Jamil book, Yeast says otherwise. They show that less-oxygenated worts don't attenuate as well as the worts oxygenated in the 8–10 ppm range, and that chronically under-oxygenated yeast over successive generations are likely to have degraded performance. Personally, I like my beers to attenuate as much as they can for their type.

Offline Robert

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Re: Formula to calculate Oxygen additions?
« Reply #6 on: September 04, 2018, 08:24:03 PM »
The Chris White and Jamil Zainasheff book got me using O2, initially for propagation and then, since I had it around, wort.  (Conventional wisdom available to me at the time favored not using pure O2 for wort.)  But if you research other sources, and search this forum, you will find a lot of information that contradicts a lot of their contentions on many points.  But most important has to be your own experience.  Lots of people around here report best results with various methods.  I personally get shorter lags and faster and more complete attenuation with a good pitch and minimal aeration, and see no degradation in successive generations.  (After all, the Crabtree effect limits oxygen's effect in yeast growth anyway.  It is useful in sterol synthesis, but is not absolutely necessary even there.)  Experiment and see what works for you.  Oxygen is only one factor, and its effects are apparently easily overestimated. 
Rob Stein
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Offline laserghost

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Re: Formula to calculate Oxygen additions?
« Reply #7 on: September 04, 2018, 08:27:39 PM »
Okay, interesting. I was planning a split batch coming up. Maybe I’ll make that the only difference. My formula vs shaking.


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Offline macbrews

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Re: Formula to calculate Oxygen additions?
« Reply #8 on: September 05, 2018, 03:17:45 AM »


If you have an active yeast pitch, wort chilled to pitching temp, and a minute of oxygen... you are going to be so close to a perfect situation that any improvement would not be noticed.

If you are seeking an exact targeted DO in your wort, you will need a DO meter. I wouldn't sweat it

Exactly

A lot of people  talk about O2 flow rates off of a cheap regulator which flows into a high resistance diffusion stone.  Who knows what the real flow rate is.  If you want to really know flow rates you need a flow meter which has a little ball that shows your true flow rate. 
I have checked DO levels in wort and have been surprised how easily and quickly you get above 8 ppm. 
And like Jim said one minute is usually plenty.  It is more important to have a big and healthy pitch.


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Offline goose

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Re: Formula to calculate Oxygen additions?
« Reply #9 on: September 05, 2018, 01:38:24 PM »
If I remember correctly, there was a seminar at one of the past Homebrew Cons about aerating wort.  They evaluated using pure O2 vs. regular air to oxygenate the wort.  Although O2 was the best, there was a relatively small difference in DO between using O2 as opposed to air.  Look at the archives of recorded past seminars on the AHA website to find it.  As I said in one other post, I have a 3/8" curved copper tube with about 25 holes drilled in it at an angle to oxygenate my wort and use air to do the trick.  The holes act as a typical kitchen faucet aerator to suck atmospheric air into the wort.  Although I should, I don't filter the air as the aerator assembly fits into the top of my conical and only sucks in air that is in the fermenter.  Plus, I am sure  that I get a bit more dissolved O2 from splashing as the wort drops to the bottom of the vessel.   I cover the 1.5" triclover fitting around the opening with a sanitizer soaked paper towel to keep outside air from coming in.  I get good attenuation in my beers and relatively short lag times with a healthy pitch of yeast.  I also  have not had any issues with contamination using this method.

I thought of using O2 and injecting it into the wort at the bottom of my conical but that would require a stainless tee, stone, and a sight glass to accomplish the task something I am not ready to pull the trigger on expense-wise as of yet.  Since what I have works, I am living by the motto "if it ain't broke, don't fix it."

Moral of the story, use whatever works for you and employ the K.I.S.S. principle whenever necessary.
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Offline a10t2

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Re: Formula to calculate Oxygen additions?
« Reply #10 on: September 05, 2018, 05:46:37 PM »
According to the book, with an aquarium pump you can only hope to get at best 8ppm DO, which is the minimum of the recommended 8–10ppm, even with extended aeration (which can be detrimental to head formation and retention, according to White).

Robert, you say it's easy to over-oxygenate with pure O2 – that's the reason behind this formula idea – to dial it in based on the particulars of the wort. But, according to the book, 60 seconds at 1 lpm for 5.3 gal of 1.077 is going to result in the optimal ~ 9.2 ppm DO. If I were to run it for a minute on that wort, and some of the O2 were to bubble out, then I'd assume I'm under 9.2 ppm.

This is why I don't recommend oxygenation for brewers who aren't willing to invest in a DO meter. Using air alone you can rely on the saturation mechanics and have some reasonable expectation of getting into the desired range (~9 ppm at 64°F, ~12 ppm at 50°F). You may end up 1-2 ppm low but that's better precision than you can expect to achieve using oxygen and making a blind assumption about flow and absorption rates.
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Offline klickitat jim

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Re: Formula to calculate Oxygen additions?
« Reply #11 on: September 06, 2018, 12:00:39 AM »
O2nation or aeration is something that I think we do, never giving a second thought. Then someone tells us wrong, so we freak out.

Offline laserghost

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Re: Formula to calculate Oxygen additions?
« Reply #12 on: September 27, 2018, 02:49:01 PM »
I have a medical regulator on the O2 tank. I wouldn't necessarily call that a "blind assumption". I'll admit, maybe I'm overthinking this, but my O2 tank and regulator + wand has yet to make a bad batch of beer, so I'll keep doing what I'm doing.

Brewing tomorrow, 11 gallons @ 1.067, split between two fermentors. San Diego Super Yeast is on the stir plate now, and have a big healthy pitch ~ 1M cells / mL. Going to make the only difference between the two fermentors the amount of oxygen that's supplied and see what differences are perceptible.

Thinking of doing one fermentor the "standard" 60 seconds at 1 lpm, and the other 60 seconds at .12 lpm

Offline LeeH

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Re: Formula to calculate Oxygen additions?
« Reply #13 on: September 28, 2018, 06:41:46 AM »
Effluent plants I have been have moved away from pure O2 and now just blow a crap load of air in.  I guess the same principle applies to a degree.  You just need more for longer. 


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