Importance of Oxygenating Wort

The science certainly supports this...and if you did get above 8 ppm it would immediately start to decrease back to 8. When you get above 8 ppm with oxygen it will also start to equalize to the standard 8 ppm, so it's important to seal the fermenter promptly. Under pressure all bets are off, can achieve some high numbers.

If air (or oxygen) is added after fermentation has started then of course the levels would increase. That's actually recommended by White/Zainasheff for high gravity wort, essentially supercharging the lag phase. I have no idea if that's what the brewers listed above are doing.

Why do you care about O2 levels in waste water? I just push the "flush" handle . . .

 

We did a test called biochemical oxygen demand, where a wastewater sample is charged with a more or less standard dose of bacteria and initial and final oxygen after a few days is measured. High BOD is generally going to mess up the ecological balance of a body of water.

 

Interesting subject and ideas.
It’s been years since I home brewed, but I do think about getting back into to it. I still have all my equipment… just not the time it seems.
I wonder if you could rig up one of those wine bottle aeration pourers to your transfer tube so all the wort passed through it.
Certainly more than some splashing and shaking, maybe even more than drilling or whisking at the surface.
Those things don’t cost much, probably worth a try.

 

After I hit the reply button I realized I should have said to put the aerator on the end of a “funnel tube”, not “transfer tube”.
I suppose it would also be a painfully slow process just thinking how slow those aerators pour.
Unless you found a really large one, or had more than one. Then you would also have to deal with the bits of debris, and filter the wort. Otherwise the aeration could clog with pieces of hops or bits barley husks.
Something to think about

 

If I understand your suggestion, it would effectively be about the same as other sorts of surface agitation, because as soon as the O2 in the wort and the atmosphere reaches equilibrium (as it's being transferred in this case), the wort will lose dissolved O2 just as fast as it gains it. IOW, you might get O2 dissolved into the wort faster, but you will also lose it faster.

 

Perhaps a situation like the old vaudeville joke:

Question: How do you get to Carnegie Hall?

Answer: Practice, practice, practice.

Mr. Wizard discussed oxygenation wort (with some emphasis in bold by me):

“OK, so here is the major assumption in this discussion: All of the oxygen that flows through your gas regulator and into the wort actually dissolves into the wort. This is the really nice thing about oxygenating with oxygen as opposed to aerating with air. Air contains about 79% nitrogen and you will always have undissolved nitrogen bubbles escaping wort, making it difficult to determine what is happening with the oxygen. When using oxygen you don’t want to see bubbles making it to the top of the fermenter. This is hard to do with wort, but you can tune your system with water. Remember, coalescence is not the idea and the desired result is a slow flow of small bubbles leaving your stone that disappear before rising to the surface. The truth of the matter is that there will be some loss in this process, but not much if the bubbles are very small.”

https://byo.com/mr-wizard/109164/

Perhaps practice flow rate, etc. with a fermenter filled with water prior to oxygenating wort?

Best of luck with your new equipment.

Cheers!

 

What size are the holes in your stone? IME, the best results are usually with a stainless sintered stone with 0.5 micron holes, and a flow rate of about 1 liter per minute. Sometimes O2 kits come with 2.0 micron stones, which isn't ideal (bubble too large, resulting in a lot of O2 escaping). But even at 0.5 microns, there will be some bubble reaching the surface.

 

One minute might be a sort of ok default, depending on flow rate, but really, bigger (gravity) worts generally need more O2 and smaller worts need less, but it's also harder to dissolve O2 into higher gravity worts, because higher gravity decreases O2 solubility.

I wouldn't say that slower is always better. I'd say "slow enough to minimize bubbles escaping, but fast enough to not lose too much due to the dissolved O2 trying to reach equilibrium with the atmosphere before the yeast get a crack at it." But unless you're measuring with a DO meter, there's some guesswork. BrewCipher includes a recommendation for oxygenation time, depending on batch size, gravity, and beer type (ale or lager), assuming a standard 0.5 micron stone and a flow rate of 1 liter per minute. If you cut the flow rate in (say) half, and double the time, I think you'd still be in the ballpark.

While it's possible to get too much dissolved O2, it's pretty hard to do. I doubt 2 minutes could significantly over oxygenate 5 gallons of wort, regardless of the flow rate/bubble size.

 

To expand on what the Norseman posted: One source of the 1L of oxygen for a minute is from White/Zainasheff who measured that rate of flow through a 0.5 micron stone into 5.3 gal of wort and found the dissolved oxygen at 9.2 ppm. They tested again for two minutes and measured 14.1 ppm. At the levels discussed here, overoxygenation is not a problem.

I tend to gas my wort at 1L/min but let it flow a little more than a minute (rather be over 9 than under) . . . the higher the OG, the more I pump. Ideally you want to see no bubbles, but that's not really possible. A good technique is to have your stone on a flexible tube and place it at the bottom of the fermenter and move it around during the process. This exposes the released O2 to more of the oxygen-depleted liquid which improves absorption. Oxygenation should be the last step before sealing your fermenter. All those bubbles of oxygen that escaped absorption are still in the headspace and if you seal promptly they will re-absorb into the wort as the yeasties start to consume the O2 in the liquid. So pitch, aerate, seal . . . and don't stop to wind your watch or scratch your ass.

BTW, oxygenating your starters is equally important.