Air Stone Bubbles Carry Oxygen and NOT Surface Agitation??

[neutrino]

Ah, source material. Thanks. Same source as the first chart? Or the source of the second chart?

Actually, the ocean article addresses the subject experimentally and computationally, describes the process and laser instruments used to take measurements, and the process of oxygen dissolution as it was observed in experimental tanks.

As I said, perhaps not clearly enough worded, I'm not saying no gas exchange takes place underwater at the surface interface of a bubble, my own link shows that it does. But the process, as described in my source, is still influenced by and made more efficient by turbulence, including the turbulence, vortices, and current created in a tank by a bubble stream.

What I'm disagreeing with is the claim of the video the original poster linked-- "It's the bubbles NOT the surface agitation." The guy in the video doesn't understand the process. His "little bit of surface agitation from that little bit of bubbles" statement eminently demonstrates this.

 

[squint]

That ocean article doesn't address whether bubble transfer or surface transfer predominates or their relative ratios. All it shows it that surface transfer is possible.

That would make Hiteshew's title technically incorrect since there's still a certain amount of surface transfer. I don't think he meant to say that there's no surface transfer whatsoever as everyone will agree that there's at least a little.

However, the myth is that bubbles only oxygenate via surface agitation. Under conditions more favorable to surface transfer, bubble transfer is still 2/3rds of all oxygen transfer.

So, I would say he's correct if he's saying the majority of the oxygen transfer is from bubble transfer and also that the myth is completely busted.

Sad that scientists figured this out 27 years ago and hobbyists who always think they're ahead of science are decades behind.

Regarding whether surface or bubble aeration is more effective, simply do a Google search for "surface vs bubble aeration sae" and keep in mind that in this context, surface aeration is much more aggressive than a rippling surface:

 

[neutrino]

I'm not simply trying to argue a point, I'm open to adjusting my understanding on the subject.

But-- Google search on that returns primarily energy efficiency comparisons in waste water treatment-- high powered surface agitation vs. high powered air diffusing equipment. This isn't home aquarium equipment. Home aquarium surface agitation won't look any more like your photo than a garden variety aquarium bubbler will create the same effect as the commercial air diffusion systems being compared in the articles-- which, again, create turbulence and mixing as part of their process.

I'm primarily focused on the process and the physics, which to me is what the question centers on-- or at least the part that interests me-- not a comparison of cost or energy efficiency of equipment you don't have in your tank, though even at that, both types of commercial equipment create turbulence that aids oxygen dissolution and mixing, which has been my point all along. The bottom line in a home aquarium is you can use either or both types of equipment to sufficient effect. Either way the process employs some form of water movement to effectively bring more water volume in contact with atmospheric gases-- unless you're doing pure oxygen or CO2 injection-- and to distribute oxygen through the system.

Sorry, but contrary to what the guy in the video implies, water bubbles just sitting there and dissolving before your eyes is not what keeps your tank sufficiently oxygenated.

Setting all of that aside-- How many natural bodies of water do you know with internal bubbler systems vs. current, turbulence, or agitation? -- even a pond with aquatic life but little intrinsic current or turbulence benefits from breezes to ripple the surface, besides an advantageous surface area to volume ratio, if not a slow current that effectively does a constant water change.

 

[neutrino]

https://cwscol.com/diffused-air-vs-mechanical-wastewater-aeration-systems

How a diffused air aeration system works

A diffused air aeration system moves air to come into contact with water. The bubbles rise to the surface of the body of water. While they rise, a percentage of the air is absorbed into the water (called oxygen transfer) and used by the microbes for respiration.

So, correct me if I'm wrong, but this appears to be your point. The question seems to center on rate or efficiency and the answer to that as I understand it would vary according to bubble size among other variables, since the smaller the bubble, the more surface area to volume within the bubble-- surface area again becomes a factor, whether you increase it through surface agitation in whatever form or by exposing water volume to greater air surface area through lots of bubbles (to use the technical term ).

So-- when you say: "Under conditions more favorable to surface transfer, bubble transfer is still 2/3rds of all oxygen transfer." I see at least two intrinsic qualifiers-- conditions favorable to bubble transfer and bubble size. How close to these favorable conditions is any given fish tank? Beside that what I'd want to see is tests of actual aquarium bubblers and their relative efficiency.

One thing I know is bubble size matters-- the microbubbles that actually dissolve most efficiently in water are smaller than the visible bubbles the guy in the video says are doing all the work. Also, a bubble stream creates turbulence while sufficient surface turbulence also introduces bubbles into the water. The two aren't mutually exclusive.

By the way-- you're in Colorado? Where roughly (if you don't mind the question). I lived in mostly in Georgetown for ten years, also on the road up to Mt Evans out of Idaho Springs.

 

[headbanger_jib]

This is very much like what the maker of the video believes.

Unless he has two tanks one with a bubbler and the other with a powerhead only, and he uses a dissolved oxygen meter to compare, this video doesn't prove anything with facts.

 

[TwoHedWlf]

This also ignores some more practical considerations.
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Air pumps are way louder and more intrusive than powerheads. Most of us have them inside our house, where an annoying buzzing noise is less than ideal, even if an air pump aerates better for the wattage.
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[islandguy11]

This also ignores some more practical considerations.
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Air pumps are way louder and more intrusive than powerheads. Most of us have them inside our house, where an annoying buzzing noise is less than ideal, even if an air pump aerates better for the wattage.
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Very true, but the downside to powerheads is that they're prone to leaking stray voltage into tanks, esp. as they age and esp. if they're cheaper ones made in China (as ~95% of people use). No such dangers to user or tank inhabitants with an air pump.

 

[neutrino]

In my mind the question is still the question, primarily addresses the process, and the answer to: Air stone bubbles carry oxygen and NOT surface agitation? is: Incorrect, both carry oxygen.

It then becomes a question of ratio in any given setup, since to this point I find it difficult to believe a 2/3 ratio is a universal law without qualifiers and applies no matter the equipment, e.g. big filter with small aquarium air pump, small air stone, or air stone producing inefficient bubble size, as many of them do. What I know is most of my tanks over the years have relied upon surface agitation only with healthy aquarium inhabitants that live long and prosper. Filters only, I don't use additional power heads.

Efficiency as I define it is if the same piece of equipment cleans my water and oxygenates my water I don't need to add something else, though this isn't true in every tank and occasionally I've added an air stone. By the way, you can quiet them down if you set them a few inches away from tank walls-- get that right and a quiet, canister filtered tank stays quiet ime.

All of that said, what Squint has said has made me interested in before/after or separate tank tests of home aquariums with filter vs. air stone oxygenation. Would be interesting to see comparisons in different conditions and different comparative filters, air pumps, etc. I will say it doesn't seem to typically require a big air pump/stone combination to put a marginal tank over the top for sufficient oxygenation.

 

[the_deeb]

This is probably obvious, but it seems like a big factor in the relative contributions of bubble vs surface gas exchange to dissolved O2 is the dimensions of the tank in question. In a very tall, narrow tank, direct absorption from the bubbles would presumably dominate, whereas in a shallow tank with large surface area, surface agitation would have a bigger relative contribution than from the bubbles.

Most natural bodies of water are going to have a much larger surface area to volume ratio than a typical aquarium, so surface agitation/turbulence is likely going to be the bigger driver of gas exchange there.

 

[squint]

I'm not simply trying to argue a point, I'm open to adjusting my understanding on the subject.

But-- Google search on that returns primarily energy efficiency comparisons in waste water treatment-- high powered surface agitation vs. high powered air diffusing equipment. This isn't home aquarium equipment. Home aquarium surface agitation won't look any more like your photo than a garden variety aquarium bubbler will create the same effect as the commercial air diffusion systems being compared in the articles-- which, again, create turbulence and mixing as part of their process.

This is exactly my point. While industrial uses won't tolerate the energy inefficiency of surface aeration, aquarists wouldn't tolerate the amount of surface agitation required for it to match bubble aeration.

I'm primarily focused on the process and the physics, which to me is what the question centers on-- or at least the part that interests me-- not a comparison of cost or energy efficiency of equipment you don't have in your tank, though even at that, both types of commercial equipment create turbulence that aids oxygen dissolution and mixing, which has been my point all along.

Sounds like the application of folk science.

The reason I bring up energy efficiency is because one can always use a massive amount of surface agitation and electricity to outperform a small air pump. That doesn't make surface agitation superior.

The bottom line in a home aquarium is you can use either or both types of equipment to sufficient effect. Either way the process employs some form of water movement to effectively bring more water volume in contact with atmospheric gases-- unless you're doing pure oxygen or CO2 injection-- and to distribute oxygen through the system.

So if I had an air pump running and let dissolved oxygen levels reach a steady state then turned it off and turned on a wavemaker of the same wattage, dissolved oxygen levels would remain the same or increase?

Setting all of that aside-- How many natural bodies of water do you know with internal bubbler systems vs. current, turbulence, or agitation? -- even a pond with aquatic life but little intrinsic current or turbulence benefits from breezes to ripple the surface, besides an advantageous surface area to volume ratio, if not a slow current that effectively does a constant water change.

What would the existence of artificial bubble aeration of a natural body of water prove? What would non-existence prove?

So-- when you say: "Under conditions more favorable to surface transfer, bubble transfer is still 2/3rds of all oxygen transfer." I see at least two intrinsic qualifiers-- conditions favorable to bubble transfer and bubble size. How close to these favorable conditions is any given fish tank? Beside that what I'd want to see is tests of actual aquarium bubblers and their relative efficiency.

Yes, the tank in the Wilhelms study has a greater surface area to depth ratio than common aquariums which should favor surface aeration. Yet bubble aeration is still responsible for the majority of oxygen transfer.

In my mind the question is still the question, primarily addresses the process, and the answer to: Air stone bubbles carry oxygen and NOT surface agitation? is: Incorrect, both carry oxygen.

No one is saying that either bubble or surface oxygen transfer is zero. The myth is that bubble transfer is negligible. HItesew's claim was that bubble transfer was the majority.