Aeration Questions

[segallis]

For the last 10 years of my almost 40 year long homebrew history I have been brewing only big beers, 1.090 to 1.100 O.G. (with a few even higher, all the way to 1.130). I pretty much always do a yeast starter, and most of the time, a two step starter. I have done maybe 10 batches where I used an O2 bottle to aerate, but normally I just allowed the cooled wort to splash into the fermenters. Every fermentation has been quick to start, vigorous blow-off tube activity within 4 hrs to 12 hrs after pitching. All have been extremely active fermentations, typically filling my 1 gal pitcher with foam and kraussen. My last 1.100 Barleywine (no O2, only splashed) overflowed both 7 gal fermonsters (~ 12 inches of headspace), with something resembling the "Blob" which didn't subside for more than 24 hours. (that motivated me to buy my 1/2 bbl conical.)

I have never had a slow start, never a slow, underactive or stuck fermentation. Never any discernible difference in beer quality or taste between the splashed vs O2 batches.

I am not interested in ever using $14 O2 bottles from Lowes again. Nor do I plan to buy a larger wending or medical grade O2 bottle.

So I have two questions for someone who only brews big beers:

1) Given my history, should I even worry about aeration, and should I expect any discernible benefit from doing so?

2) Given these facts* from various sources:

• O2 can be added up to 24 hrs after pitching for big beers
• Aeration with air cannot achieve the same levels of O2 as from a pure O2 bottle
• An aquarium pump is slow, maybe 15 to 45 minutes required

I get that yeast need O2 to do their job. I doubt there is much difference between the O2 demand for a big beer vs a low O.G. beer, except for the duration of the fermentation. So I am wondering why starting with 15 ppm O2 at the start and adding nothing the rest of the fermentation is any different from maintaining 8 ppm O2 by continually adding plain air for, say, 24 hours.​

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What is the difference between these two scenarios???​

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So what about the idea of running an aquarium pump & stone continuously for the first 24 hours after pitching?​

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[Broken Crow]

If the difference that matters to you is what can be measured in a lab, then you'll probably want those with lab gear to answer this... If the difference that matters to you is the satisfaction you get from your brews, then it seems you've answered your own question:

Never any discernible difference in beer quality or taste between the splashed vs O2 batches.

...If you just wanted to sound it out: I validate you. I too may or may not use external O2 again...for most of my brews I don't, but I might try it for some new recipe if it doesn't turn out the way I hoped the first time without the bother.

 

[KeizerBrewr]

There's Brulosophy xbmt's out there that show oxygenation and aeration are different obviously, but still end up with the same result and no notable differences in beer quality. I still use a sparge nozzle on my hose as it runs into my fermenter going through a mesh strainer. At the homebrew level, I really can't justify the expense of O2, when shaking and being vigorous racking to the fermenter accomplishes the same thing. Healthy yeast is a big contributor to the finished product.

 

[day_trippr]

Don't see any data on FG. I think that's key wrt the benefits of oxygenation.

Yeast need oxygen to multiply, and when pitching to a monsterous brew it'd be helpful to optimize growth so the resulting population can hammer at the high OG. I always use oxygen on my brews, and use even more for my big beers (like an 11-12% imperial stout) so they finish with a respectable FG and don't end up as pancake syrup

That said, if the OP is satisfied with the results of their current process I would not advise them to change...anything...

Cheers!

 

[segallis]

Don't see any data on FG. I think that's key wrt the benefits of oxygenation.

Yeast need oxygen to multiply, and when pitching to a monsterous brew it'd be helpful to optimize growth so the resulting population can hammer at the high OG. I always use oxygen on my brews, and use even more for my big beers (like an 11-12% imperial stout) so they finish with a respectable FG and don't end up as pancake syrup

That said, if the OP is satisfied with the results of their current process I would not advise them to change...anything...

Cheers!

What is your typical F.G. for your 11% stouts? My Quads usually finish around 1.012 +/-. The highest I typically see is maybe 1.019, but I also mash at higher temps since I prefer more body and flavors offered by unfermentables. I did one experiment where I took a sample after fermentation had ceased, added O2 and new yeast to see if there was anything there for them to ferment - no change in S.G., so I tend to beleive my F.G. is what it is regardless of whether I started with O2.

 

[segallis]

There's Brulosophy xbmt's out there that show oxygenation and aeration are different obviously, but still end up with the same result and no notable differences in beer quality. I still use a sparge nozzle on my hose as it runs into my fermenter going through a mesh strainer. At the homebrew level, I really can't justify the expense of O2, when shaking and being vigorous racking to the fermenter accomplishes the same thing. Healthy yeast is a big contributor to the finished product.

Since my move to a 1/2 bbl conical, shaking is not possible. I could still splash with a filler hose in the top, but I prefer doing the liquid transfer from BK to Fermentor via pump connected to the bottom TC port of the fermentor, so I won;t get any splashing during the fill.

Which Is why I'm considering just running an aquarium pump and stone for the first 12 or 24 hours. Any down side to this?

-G

 

[KeizerBrewr]

Running it that long doesn't help any more than running it for a half hour. But that would work

 

[day_trippr]

What is your typical F.G. for your 11% stouts?

My recipe OG is 1.110, FG is usually between 1.022 and 1.025...

Cheers!

 

[segallis]

Running it that long doesn't help any more than running it for a half hour. But that would work

I'm trying to understand the math behind this. Suppose the goal were to use pure O2 to acheive 16 ppm total dissolved oxygen in the wort. That would be about 768 mg total dissolved oxygen fo 12 gallons or wort. Using air for 30 minutes could acheive around 8 ppm or 384 mg tital dissolved oxygen. So obviously the yeast will consume the dissolved oxygen more quickly in the seconds case. Now if you run the pump for, say, 24 hours, you will be maintaining 384 mg total oxygen even as the yeast consume the oxygen.

I have no idea how much oxygen will be consumed ny the yeast inthe first 24 hours, but suppose it was about 150 mg, then running the pump for 24 hours would the same as if the wort started with 534 mg of oxygen, or 11 ppm.

What am missing here?

 

[day_trippr]

The theory seems sound to me but then again wth do I know about yeast respiration needs beyond what's been written by others.
What we need here is a yeast scientist to bat the ball around to provide fidelity to the intuition that continuous oxygenation to 8 ppm for 24 hours likely is superior to one-shot pure O2 to 12-16 ppm...

Cheers!