Air Stone Bubbles Carry Oxygen and NOT Surface Agitation??

[H]-[H]

I know this topic has been debated many times over the years and even I myself have come to the conclusion that oxygen does not come from the air stone bubbles but from surface agitation caused by the bubbles..
However, I stumbled upon this video recently and wanted to know the feedback from experienced fishkeepers here regarding this topic again..

 

[BIG-G]

Without a true test under controlled environment and actual documentation of the results, it’s just someone on the Internet making claims.

I’ve watched some of Cory’s videos I have never seen what this guy is referring to.
I would like to know if anyone has done real testing. If anyone has any links to this data I would like to see it.

 

[islandguy11]

I'll wait for the more scientifically inclined to comment (and completely agree with BIG-G), but I'll add that I just checked out several of my tanks, all of which have air stones of various sizes (and micro bubbles to bigger bubbles) -- and personally I cannot see any bubbles disappearing or dissolving into the water (as he says about 4:45 in the video).

I don't know, he could be right, but for myself I take a lot of what this particular YouTuber says with a grain of salt -- he's got a couple of videos about nitrate levels (that he starts in a very similar way, talking about how people believe and pass on certain 'myths' in the hobby), then goes on to basically argue that 40-80 ppm nitrates are A-OK and nothing to really worry about. I disagree but that's getting off topic.

Back to the question at hand, I also don't see where it really matters either way, regardless of whether the tank is being oxygenated by the bubbles in the tank, or at the top (with said oxygenated water then be carried back down to lower levels), it would still be about the same net positive effect wouldn't it?

 

[Hendre]

Bubbles have a surface area interacting with the water, so naturally some oxygen will diffuse. It's all about any interaction between water and air. Bubbles and surface afaik...

 

[squint]

 

[Rocksor]

There are enough scientific articles out there, especially from the aquaculture industry, that have delved into the most efficient and least costly way of introducing more oxygen into water system versus spending more money on pumps for water agitation. No need to conduct your own experiments.

Most fishkeepers aren't measuring dissolved oxygen levels.

 

[squint]

 

[squint]

I don't know where I read it but someone pointed out that pumping air will always be more effective for the same amount of energy expended because water simply requires more energy to move.

Another thing that people don't realize is that water pressure enhances gas transfer. That's why I always put air stones as deep as possible.

 

[neutrino]

In what way do these charts prove the degree to which the air bubbles diffused oxygen directly to the water before they break the surface? Chart 1 that makes this claim would need to explain exactly how they measured this and how, in what's apparently the same tank, they could accurately separate three measurements-- O2 dissolution from surface turbulence created by a filter or pump, O2 dissolution from surface turbulence caused by bubbles reaching the surface, and O2 dissolution directly from bubbles while still in the water column. For the last to be a convincing measurement, the system would need to be enclosed to eliminate surface gas exchange... or perhaps sufficiently stratified to accomplish something similar-- in which case, pressure at depth becomes yet another variable, so that probably doesn't work either.

Not to say it's not possible, but the dynamics involved are complicated and still depend largely on turbulence -- read this.

I need to see something more convincing than a chart form an unknown source that doesn't appear to conduct a well constructed experiment. As it is, all that appears to be established in the charts is a comparison of equipment, not the physics of the process.

 

[squint]

They aerated with nitrogen gas and air and measured the difference in dissolved oxygen levels. If surface agitation was the source of nearly all oxygen transfer then DO levels would be similar but they're not even close.

Gas Transfer in Diffused Bubble Plumes

The gas transfer in aeration systems is broken into two processes: gas transfer at the bubble interface and gas transfer at the water surface. Experiments were conducted to separate these two sources of dissolved gas. Oxygen absorption was measured in a laboratory tank with air being diffused...

digitalcommons.unl.edu

This study actually addresses the question whereas a paper on ocean waves doesn't seem particularly on point.