Oxygenation question : do I really need a protein skimmer?

[Fish Fan]

Yes, air stones and air pumps use ~7 times less power to achieve the same dissolved oxygen levels. This is consistent with experiments done by the wastewater treatment industry which switched from surface aeration to bubble aeration decades ago.

Air stones don't seem to work very well in very shallow water (3-4").



This is a very common misconception. There have been a number of studies done to separate the oxygen transfer of a bubble plume into its bubble transfer and surface transfer components. The earliest I'm aware of (from 1992) alternatingly diffused nitrogen gas and air and estimated that 2/3rds of the total oxygen transfer is bubble transfer.

More recent studies done at bench scale (closer in size to aquariums) found it to be even higher (89-97%).

I’ve never understood why folks discount gas transfer inside bubbles. They do add surface area of transfer, and are also under pressure, forcing more O2 into the water.

I've heard all my life, including in school for bio and chem, that nothing really happens until the bubbles burst at the surface, but I'll stand corrected here :) Thank you for the info!

 

[Randy Holmes-Farley Verified Community Expert]

I've heard all my life, including in school for bio and chem, that nothing really happens until the bubbles burst at the surface, but I'll stand corrected here :) Thank you for the info!

I’ve heard it all the time too. It may be the case that ordinary bubblers accomplish as much or more, maybe much more at the water surface. Some aeration methods make fairly small bubbles, however, and the small bubbles have a lot more surface area per air volume.

 

[Dom]

Hi all,

I’ve recently had some trouble with my new clownfish couple and it’s now seeded some anxiety over if I’m correctly receiving oxygen in my tank water.

How to know if my fish are having trouble getting oxygen? Only my clowns (which have been in the tank for a week now) have been breathing fast and acting weird in the last two days, all other fish that have been in the tank for multiple months are acting like usual and appear fine.

I’ve always just had two powerheads pointed at the surface (every spot of the water surface is moving), an HOB filter and a surface skimmer and it’s been working really well. Is this actually enough or should I replace the surface skimmer with a protein skimmer?

TIA!

There is a possibility that your week old clowns are ill. The behavior they are exhibiting (fast breathing) is a symptom of 1 or more diseases.

That the other fish have not exhibited fast breathing or are not "acting weird" may be that they haven't become sick yet.

But I'm jumping to conclusions...

 

[Ben's Pico Reefing]

Do you have a lid on your tank? If so what kind? Is it creating a sealed like cover or is it just net/screen? Can you also share pic of the tank setup

As others stated oxygen exchange is more about contact time and surface area. More agitation the better. What one person calls a lot of flow or surface movement may not be a lot to others.

I agree though this does sound like more of a disease issue. But what is your ammonia and nitrate. It has to be really high to effect fish but let's just rule this out anyways. Also what is your current salinity?

 

[Fish Fan]

I’ve heard it all the time too. It may be the case that ordinary bubblers accomplish as much or more, maybe much more at the water surface. Some aeration methods make fairly small bubbles, however, and the small bubbles have a lot more surface area per air volume.

Thanks for your help here! I do know the bubble size counts, I remember wooden air stones for air driven skimmers :)

 

[Malcontent]

I've heard all my life, including in school for bio and chem, that nothing really happens until the bubbles burst at the surface, but I'll stand corrected here :) Thank you for the info!

I was a bio major and chem minor and the mass transfer of bubble plumes never came up.

There never was a time when scientists or engineers believed that surface transfer was dominant so it's unlikely they would be teaching that to students.

Where I do hear it all time was on aquarium forums (RIP) in the past or social media today. Of course, none of those people had any evidence to offer other than their intuition.

 

[Fish Fan]

I was a bio major and chem minor and the mass transfer of bubble plumes never came up.

There never was a time when scientists or engineers believed that surface transfer was dominant so it's unlikely they would be teaching that to students.

Where I do hear it all time was on aquarium forums (RIP) in the past or social media today. Of course, none of those people had any evidence to offer other than their intuition.

Well, I am also a bio major, chem minor, and one of my bio teachers back in high school was a PhD and into tanks, and had several going in his room. I'm petty sure that's who told me that, which was many years ago, but it's been proliferated through the hobby for years as well. As I said, if I'm mistaken, I stand corrected.

 

[Subsea]

I was a bio major and chem minor and the mass transfer of bubble plumes never came up.

There never was a time when scientists or engineers believed that surface transfer was dominant so it's unlikely they would be teaching that to students.

Where I do hear it all time was on aquarium forums (RIP) in the past or social media today. Of course, none of those people had any evidence to offer other than their intuition.

Five years ago, I got my indoctrination on oxygen transfer at a shrimp farm run by Texas A&M at Flour Bluff, Texas. They had oxygen sensors to measure & document the process. The production rate of shrimp was 1 kilo per 1 cubic meter of water. At the end of the tour, I was allowed to catch a dip net full of large shrimp to bring home.

The research grant was to raise shrimp in inland hatchery and my contribution was to supply seaweed culture to clean up spent water to be reused in the next batch crop.

Texas is under severe drought restrictions and while ground water was available, it was decided early on that being good stewards of ground water was important as good citizenship. So, once shrimp were harvested from large indoor tanks, the water was transferred to outdoor lagoons full of Gracilaria Hayi and Texas sunshine, that grew seaweed and removed inorganic nutrients so water could be reused after uv sanitized before being returned to next batch culture.