Question for first time oxygenating beer

I scored a full medical O2 bottle and regulator on Craigslist. My question is with a .5 micron stone, how much O2 should I flow? The regulator is in liters per minute, 1 through 15. Also, how long should I flow per 5 gallons?
Thanks

fwiw, The best one can ever obtain using "air" is 8ppm, while White Labs says pure O2 at 12ppm is a good target for normal gravity beers, and further indicates higher won't hurt (though they don't write how much higher). Otoh, I've read in the past that a 40ppm O2 level is close to the "toxic to yeast" zone, but I'm not sure if that's the current wisdom (I've been told things have changed wrt understanding yeast).


Anyway...I use an SS .5 micron airstone at the end of an acrylic tube (hunk of racking cane) that reaches the bottom of my 6.5 gallon carboys, running pure O2 through a volumetric regulator (like you'd typically find next to a hospital bed) set for .5 liters per minute.

For my "normal gravity" 1.050, 5.25 gallon (21 liter) "ready to pitch" batch size - and assuming a 50% absorption rate - that works out to the mid teens for ppm (like 15-16ppm). I'll add another 30 seconds for every 10 points of OG above the 1.050 baseline.

My totally spitballed absorption rate is the proverbial fly in the ointment - I truly have no idea what one could assume for the O2 absorption rate using a .5 micro stone at .5 LPM for say a 1.050 brew at 70°F.

I don't own a DO meter (rather put the ~$165 into upgrading to more stainless stuff but I've been doing this for a couple of years and my starts are always very quick, I've never had a stuck fermentation, and nothing has crawled out of my carboys to attack me in the middle of the night

I'd actually be very interested if someone with a DO meter has done the testing with a similar setup - especially if they've recorded some numbers for different density brews.

hth

Cheers!

[edit] On the other hand, there is this article, which assumes 100% absorption and calculates that you'd only need .112 liters of pure O2 to reach the 8ppm level, thus .224 for 16ppm.

So...the 3 liters I typically use would be way higher - like around 214ppm making the same assumptions. Obviously chemistry and all those moles 'n' stuff was never my strong suit

I'm ambivalent about changing my ways though. Old and stubborn, that's me...

[edit2] Ok, this has definitely caught my curiosity, and as I didn't have much else to do tonite (Sox already slaughtered the Damned Yanquis this afternoon) I've been searching the web to get a better grip on this whole thing. Still haven't found a definitive answer - I have a problem with the BYO article cited above wrt the 100% absorption assumption, as it is well known that absorption decreases as wort SG increases, which to me means it can never be 100%.

I also found a couple of articles that claimed it is pretty darned difficult to negatively affect yeast via a single, pre-pitch blast of O2 (post pitch is a different story, but I never do that). As well, other articles claim there's not much reason to exceed O2 ppm in the low teens, and still other articles claim the whole "O2 level toxic to yeast" is in fact a myth (jeeze, I have a lot of books written by "notables" over the last 10-15 years that totally disagree with that - guess I'm gonna have to toss 'em!)

Finally, this BYO article indicates that even with my apparently insane O2 injection regimen I'm likely not driving the ppm above roughly 43. Otoh, it also indicates I'm obviously wasting a lot of O2

So, I'm stubborn, but I'm also frugal, so I'll be cutting way back to around 60 seconds @ .5 LPM (instead of 6+ minutes) on my next batch, and observe the resulting lag time, FG, and any ester notes, to see if there is anything obviously different.

Cheers again!

day_trippr said:

For my "normal gravity" 1.050, 5.25 gallon (21 liter) "ready to pitch" batch size - and assuming a 50% absorption rate - that works out to the mid teens for ppm (like 15-16ppm). I'll add another 30 seconds for every 10 points of OG above the 1.050 baseline.

Click to expand...

Thanks for the detailed reply. One question, how long do you run at .5 lpm for 1.050 beers?

Thanks again

Revelation!

I actually had a copy of Chris White's Yeast but hadn't gotten around to cracking it open until this week. And now that I've read it about halfway through I'm finding it an amazing read.

Anyway, I really hadn't come to a satisfying conclusion re: my previous post to this thread - other than noting to myself that percent volume does not equal parts per million ) This discomfort was mostly related to my firm belief that oxygen will not dissolve into wort anywhere near 100% under any normal circumstance - which runs counter to the assumption that the Wilder article so easily made.

But I had no way to determine just what the absorption rate could be, and I could not find a single article that actually pumped a measured amount of pure O2 into a specific volume of wort at a specified gravity at a specific temperature through a typical sintered air stone at a specified rate and measured the resulting O2 content. Sheesh - you'd think someone with a DO meter would have written up actually using it!


So a couple of days ago I came upon page 79 in Yeast. And there, lo and behold, was exactly what I had been looking for! White had done the work for me and put the results in a table!

He used a 20 liter batch - near 'nuff to the 5.25 gallons I usually load into a carboy. The SG was 1.077 (18.7 °P) - pretty close to my wheelhouse (my smallest brews are in the low 60s). The temperature was 75°F, and he used a .5 micron sintered stainless stone, running 1 liter per minute.

30 seconds provided 5.12 ppm
60 seconds provided 9.20 ppm
120 seconds provided 14.08 ppm

When I plotted White's three data points the trend shows oxygenation is not linear with time - the gain clearly drops. If I add a data point for 180 seconds that fits the extrapolated curve, I'd expect the result to be roughly 17 ppm.



If one can discount any difference in absorption based on flow rate, White's 120 seconds at 1 LPM would equal 4 minutes at .5 LPM, and my extrapolated datapoint of 180 seconds for 17 ppm would equal (wait for it) 6 minutes at .5 LPM!

Hmmm...Maybe I wasn't that insane after all


White followed that table with a chart plotting the effect of O2 on fermentation, which clearly showed the 14.08 ppm wort finished faster than the lower oxygenated worts, and attenuated more fully than all but the 9.2 ppm wort.


Soooo....When I gassed up the IPA I brewed Sunday I went ahead and hit it with the full four minutes of pure O2 at .5 LPM - and felt good about it And twelve hours later the yeast in the two carboys are rockin' - like usual.


There's a lot more information regarding oxygenation in White's Yeast, particularly when dealing with higher gravity brews (pretty much anything over 1.082 SG/19.8 °P), including the interesting recommendation to use a second dose of pure O2 12 to 18 hours after pitching). I also found fascinating his take on the general state of oxygenation in small scale commercial brewing - his testing found most small breweries had no idea how well they were gassing up their worts (and they can actually afford a DO meter!)

For that and a whole lot more wrt yeast, I definitely recommend this book...

Cheers!

The following data is for 5.5 - 5.75 gallons of wort in a glass carboy, oxygenating with a .5 micron stone at the end of a wand and measuring DO with a Milwaukee SM600. Hope this helps. Click on the pic to enlarge:

Thanks for posting that table, dstar26t! It totally kicks the cr@p out of the "100% absorption" assumption in the Wilder BYO article!

Cheers!

This is really good info. I am curious what the relationship between liters per minute and parts per million is. What I mean is this. If at 1 lpm you get X ppm, at .5 lpm do you get .5X and at 2 lpm do you get 2X? I bet that it is not a linear curve just like it is not with time.

cfrazier77 said:

This is really good info. I am curious what the relationship between liters per minute and parts per million is. What I mean is this. If at 1 lpm you get X ppm, at .5 lpm do you get .5X and at 2 lpm do you get 2X? I bet that it is not a linear curve just like it is not with time.

Click to expand...

That's a good question, for which I have no data, nor the means to generate same with a decent degree of confidence.

But, just for grins, I'm looking at dstar26t's table, specifically the very first and very last table entries, which are the closest pair I see wrt wort temperature and specific gravity. The first entry used 3 LPM for 90 seconds, resulting in a measure O2 content of 14 ppm, while the last entry used 1 LPM for 82 seconds, resulting in 10.0 ppm. If I scale the latter entry up to 90 seconds (and obviously assume a linear function) the result would be 11 ppm. At face value, this would indicate the higher rate of oxygenation resulted in greater absorption, by roughly 30%.

I wouldn't bank on that conclusion, but at the worst, they really aren't all that far apart. And the wort in the first table entry is 6 points lighter SG than the last, which would favor a little better absorption for the former, bringing the two data points a bit closer in Real Life®

In short, unless someone has generated some comparative data and proffers it here - or Santa brings me a DO meter - I'll be ok assuming absorption isn't significantly affected by the rate of oxygenation...

Cheers!