I notice other's don't use air pumps/stones in SW fish only tanks so how do you keep the fish from suffcating?

[4ktvs]

My dad ran saltwater tanks for nearly 20 years before deciding the work wasn't worth it and in his setups he used air pumps with air stones. However the amount of salt that ended up on everything was quite a lot and actually wanted to know how you deal with that before it becomes a mess. I've also read about the losses that happen and know from his experience they happen in the saltwater fish keeping hobby. But it was really sad when the blue spot sting ray passed away after doing well for 3-4 years. He was the best and people that came over thought he was really cool. If I didn't read about how unlucky people have been with them plus the cost I'd really want to give it a shot right off the bat.

Getting back to the subject at hand. I've read some about gas exchange, but nothing has given me a good idea on how to know there is enough going on for the fish in the tank to get by without suffocating. Asking because I am considering setting up my own first saltwater fish only tank. Any insight here would be of help.

 

[homer1475]

Bubblers actually do not add any oxygen to the water. What they do is to move the water via bubbles, and agitate the surface for gas exchange. The actual bubbles do nothing.

The easiest way to accomplish this without bubblers, is power heads pointed at the surface, or a hang on the back filter that agitates the surface. Of course a sump with falling water will also produce plenty of oxygen for your fish.

Bubblers as you already noted tend to make a mess with salt spray, this is the number one reason we do not use them is SW.

 

[Tamberav]

My dad ran saltwater tanks for nearly 20 years before deciding the work wasn't worth it and in his setups he used air pumps with air stones. However the amount of salt that ended up on everything was quite a lot and actually wanted to know how you deal with that before it becomes a mess. I've also read about the losses that happen and know from his experience they happen in the saltwater fish keeping hobby. But it was really sad when the blue spot sting ray passed away after doing well for 3-4 years. He was the best and people that came over thought he was really cool. If I didn't read about how unlucky people have been with them plus the cost I'd really want to give it a shot right off the bat.

Getting back to the subject at hand. I've read some about gas exchange, but nothing has given me a good idea on how to know there is enough going on for the fish in the tank to get by without suffocating. Asking because I am considering setting up my own first saltwater fish only tank. Any insight here would be of help.

You use poweheads and proper flow. Skimmers also help but that is like their bonus purpose and just poweheads is enough.

Bubblers are never used, only in like a 2 gallon reef.

A stingray probably needs something in the 300g range and set up for their needs and not so much a reef tank. That would be an expensive endeavor for a beginner.

 

[ZoWhat]

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[atoll]

Not that my fish would suffocate without but I use an Oxydator to keep my oxygen at optimal levels. Never heard of Oxydators? So have the majority in saltwater fish keeping but the word is getting out more and more.

 

[Azedenkae]

My dad ran saltwater tanks for nearly 20 years before deciding the work wasn't worth it and in his setups he used air pumps with air stones. However the amount of salt that ended up on everything was quite a lot and actually wanted to know how you deal with that before it becomes a mess. I've also read about the losses that happen and know from his experience they happen in the saltwater fish keeping hobby. But it was really sad when the blue spot sting ray passed away after doing well for 3-4 years. He was the best and people that came over thought he was really cool. If I didn't read about how unlucky people have been with them plus the cost I'd really want to give it a shot right off the bat.

Getting back to the subject at hand. I've read some about gas exchange, but nothing has given me a good idea on how to know there is enough going on for the fish in the tank to get by without suffocating. Asking because I am considering setting up my own first saltwater fish only tank. Any insight here would be of help.

Juat need to agitate the surface. I don't have a skimmer or anything fancy, just had to make sure there is plenty of gas exchange at the water-air interface.

 

[Paul B]

It is almost impossible to not have enough oxygen for the fish unless you totally over fed and the water is cloudy or something big died in there. Like your cat.

 

[Alexopora]

Bubblers actually do not add any oxygen to the water. What they do is to move the water via bubbles, and agitate the surface for gas exchange. The actual bubbles do nothing.

The easiest way to accomplish this without bubblers, is power heads pointed at the surface, or a hang on the back filter that agitates the surface. Of course a sump with falling water will also produce plenty of oxygen for your fish.

Bubblers as you already noted tend to make a mess with salt spray, this is the number one reason we do not use them is SW.

+1 The actual gas exchange occurs at the surface when its agitated. Basically the bubbler is just doing the same job as any pump that agitates the surface (be it powerheads tilted towards to the surface or hob filters). For my tanks, its a combo of both powerheads slightly positioned towards the surface and a hob filter. But i think most of the agitation is done by the powerheads as I set my HOB to low speed to prevent splashing and to facilitated in anaerobic filtering.

As long as you see surface agitations in the form of waves and not still water, your tank should have sufficient oxygen.

 

[Malcontent]

Wilhelms and Martin 1992 diffused nitrogen gas and air. Diffusing air resulted in much higher dissolved oxygen levels which busted the myth that bubbles only oxygenate via surface agitation 30 years ago:

In 2018, Lee used CFD to further refine the model for bubble plumes and found that >95% of oxygen transfer is bubble transfer:

Numerous studies by the wastewater industry have found that bubble aeration is much more effective than surface aeration:

I've found that a 3.5 W air pump and a 24 W wavemaker positioned to maximize surface agitation were roughly equal in performance, resulting in ~6.3 mg/L dissolved O2 (freshwater tank). Without the air stone, levels dipped as low as 3.9 during the day (which is not healthy) despite the wet/dry filter.

 

[homer1475]

Wilhelms and Martin 1992 diffused nitrogen gas and air. Diffusing air resulted in much higher dissolved oxygen levels which busted the myth that bubbles only oxygenate via surface agitation 30 years ago:

In 2018, Lee used CFD to further refine the model for bubble plumes and found that >95% of oxygen transfer is bubble transfer:

Numerous studies by the wastewater industry have found that bubble aeration is much more effective than surface aeration:

I've found that a 3.5 W air pump and a 24 W wavemaker positioned to maximize surface agitation were roughly equal in performance, resulting in ~6.3 mg/L dissolved O2 (freshwater tank). Without the air stone, levels dipped as low as 3.9 during the day (which is not healthy) despite the wet/dry filter.

And all that means absolutely nothing, because no one uses bubblers in SW. Ok maybe a FOWLR tank, but certainly no bubblers in a reef.

No one wants to be cleaning salt spray off their walls every day. We don't use bubblers in SW for that exact reason.

And all that "science" pertains to freshwater, not SW(and waste water treatment plants at that). So it really doesn't pertain to anything(I can google too).

I do wonder though, if the same would apply to SW? But somehow I think the SW would act differently.

 

[Malcontent]

And all that means absolutely nothing, because no one uses bubblers in SW. Ok maybe a FOWLR tank, but certainly no bubblers in a reef.

No one wants to be cleaning salt spray off their walls every day. We don't use bubblers in SW for that exact reason.

I'm not disputing this. In fact, they're messy in fresh water too. What I am disputing are the ideas that bubbles only oxygenate by agitating the surface and that filters are enough.

And all that "science" pertains to freshwater, not SW(and waste water treatment plants at that). So it really doesn't pertain to anything(I can google too).

Why did put science in quotes?

Everyone in the hobby says that bubbles only oxygenate by agitating the surface. I never accepted this as true without evidence but it took me several years of on and off Googling to find the first study that addressed the issue. I find it offensive when you say "I can Google too" because in all likelihood you would have not found anything. Before my work, there was no scientific evidence on either side of the debate, just a bunch of people using their intuition (and getting it wrong).

Bubble aeration is still more efficient in clean water:

I do wonder though, if the same would apply to SW? But somehow I think the SW would act differently.

Download OpenFOAM and run the Lee study using saltwater and see if it goes from 95% bubble transfer in freshwater to >80% surface transfer in saltwater.

Why are people always so hostile when confronted with evidence that they believe in a myth? Every time I bring up scientific evidence that contradicts some widely held belief in the hobby, people bring out the pitchforks. This is mostly in FW forums where I rarely dare to challenge the orthodoxy. I thought it was safe here since SW people are a bit more science-based but I guess I was wrong.

 

[homer1475]

My whole point is that study is in fresh water, not saltwater. Therefore the "science" you posted isn't of any importance.

No pitchforks here, just posting why I think that what you posted doesn't apply.


I put science in quotes simply because tone cannot be reflected in written word. My intention was to point out the science you posted pertains to freshwater waste water treatment plants.

You just addmited yourself you found the research by googling. I can google too. LOL take it what ever way you want. My intention was never to be combative, or hostile. Sorry if it came off that way.

 

[brandon429]

In both freshwater and sw, air stones beat pumps in any arrangement for oxygenation due to surface boil, all links agree. They’re not used commonly in saltwater because we don’t need help with oxygen, and the salt creep. I know about a thousand reefs that use air stones though here’s the nicest one

I know folks don’t consider those reefs but my goodness look at the top shelf sps, eight years, it’s a reef. It’s just fishless




don’t be volumists I like to say, it’s all about the #of years we throw coral in the trash for export because so much is produced nobody wants the unattached mass. When you are throwing away sticks of growth to make room for new growth that others would pay $50 a frag for if barely attached to a frag plug, you may be pico reefing a long time

 

[brandon429]

I would have never known the efficiency differences between laminar flow / surface boil vs eddy currents were it not for an old website called aquatic-eco.com which is now closed. The physics blurbs they’d write in their sales magazine were just amazing. They were a supply company like Carolina biological and they sold parts to zoos and whale exhibits

to this day ive never seen another company casually advertising a $75,000 skimmer that is eighteen feet tall and requires a forklift to install.

 

[Malcontent]

My whole point is that study is in fresh water, not saltwater. Therefore the "science" you posted isn't of any importance.

No pitchforks here, just posting why I think that what you posted doesn't apply.


I put science in quotes simply because tone cannot be reflected in written word. My intention was to point out the science you posted pertains to freshwater waste water treatment plants.

You just addmited yourself you found the research by googling. I can google too. LOL take it what ever way you want. My intention was never to be combative, or hostile. Sorry if it came off that way.

"Isn't of any importance?" I think it casts a lot of doubt on the idea that bubbles only oxygenate via surface agitation in saltwater.

Are FW and SW that different such that the results would be completely flipped? Remember that in FW it's >95% bubble transfer and <5% surface transfers. For it to be true that bubbles only oxygenate via surface agitation in saltwater, I would expect it to be >90% surface transfer in saltwater.

Did you run the OpenFOAM simulation yet? Or do some Googling to find a paper explaining why results would be completely different in saltwater?

Google doesn't make things easy. It can't (yet) read your mind and instantly give you the exact results. If you're not familiar with the jargon of a particular field you don't use the correct search terms and have to wade through page after page of irrelevant results.

If you think it's so easy try finding scientific evidence for or against the idea that fish release chemicals that stunt their growth. That didn't take nearly as much effort as finding studies on bubble plumes.

 

[homer1475]

Now someones getting hostile.

I'm out. Sorry if I offended you in any way.

 

[WVNed]

When common sense is replaced by "science", myth and legend.
It used to be common knowledge that bubbles work by increasing the square footage of the air water interface for gas exchange. That would apply to both fresh and salt water.
Now we get the stuff in this thread.

 

[RipVanWinkle]

bubbles are good

I agree.

 

[atoll]

Juat need to agitate the surface. I don't have a skimmer or anything fancy, just had to make sure there is plenty of gas exchange at the water-air interface.

Gas exchange as in

When common sense is replaced by "science", myth and legend.
It used to be common knowledge that bubbles work by increasing the square footage of the air water interface for gas exchange. That would apply to both fresh and salt water.
Now we get the stuff in this thread.

My understanding is that CO2 is readily disolved in seawater or freshwater while O2 isn't in comparison. CO2 is also a heavy gas which congregated more in the lower layers. These lower levels of water need to be brought to the surface and the surface agitated to gas off the CO2. Lots of water movement bring water from below should do this. Oxygen levels have no bearing on CO2 and oxygen not being as soluble is more likely to be deficient. I have an efficent skimmer but also use an Oxydator to keep my Oxygen levels at optimum levels. On the reef esp around breakers oxygen I'd always at saturation point and in fact often exceeds saturation point according to a scientific study I read some years ago. Mixing all water layers seems a good idea to me along with limiting CO2 in the aquarium room.

 

[Malcontent]

When common sense is replaced by "science", myth and legend.
It used to be common knowledge that bubbles work by increasing the square footage of the air water interface for gas exchange. That would apply to both fresh and salt water.
Now we get the stuff in this thread.

I don't know about that. I commonly see people (in FW forums) arguing that the surface area of bubbles is less than that of the tank, that the "dwell time" isn't long enough, etc. I've seen several crude attempts to calculate the cumulative surface area of a bubble plume but it doesn't consider other factors such as water pressure.

The Lee study used a much more sophisticated model which took a dozen Xeon processors eight hours to compute. I found it a bit more persuasive than the calculations done by hobbyists.

Some unrelated but fascinating bubble plume simulations: