# Help Understanding Air Stones



## christinecrites (12 Apr 2021)

I was hoping someone could help be understand the best placement for my air stone. My understanding is that it’s not the oxygen bubbles being released in the water but about them breaking at the surface to create a gaseous exchange. Every YouTube video I watch the airstone is placed at the bottom of the tank. I have suction cups on mine (it looks like a CO2 Diffuser). Is there a benefit to having it low in the tank or closer to the surface for more surface agitation?


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## Nick potts (12 Apr 2021)

Having it lower can have benefits, as the bubbles are pulled up through the water column they create flow, and mix the water lower down with the surface layers. It is only minimal but every little helps


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## christinecrites (12 Apr 2021)

Nick potts said:


> Having it lower can have benefits, as the bubbles are pulled up through the water column they create flow, and mix the water lower down with the surface layers. It is only minimal but every little helps


Thanks Nick! I could certainly use all the help I can get!


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## Mark Nicholls (12 Apr 2021)

There is only a minimal amount of oxygen created by bubbles. 
Extra oxygenation takes place in two ways:
1) The column of bubbles draws water from the bottom of the tank to the surface where it will absorb oxygen from the atmosphere. 
2) The upward flow creates ripples which increases the surface area meaning that more oxygen is in contact with the waters surface. 

To optimise oxygenation and flow, there should be a smooth, steady flow of bubbles. Too much air creates turbulence which slows the current down


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## christinecrites (12 Apr 2021)

Mark Nicholls said:


> There is only a minimal amount of oxygen created by bubbles.
> Extra oxygenation takes place in two ways:
> 1) The column of bubbles draws water from the bottom of the tank to the surface where it will absorb oxygen from the atmosphere.
> 2) The upward flow creates ripples which increases the surface area meaning that more oxygen is in contact with the waters surface.
> ...





Mark Nicholls said:


> There is only a minimal amount of oxygen created by bubbles.
> Extra oxygenation takes place in two ways:
> 1) The column of bubbles draws water from the bottom of the tank to the surface where it will absorb oxygen from the atmosphere.
> 2) The upward flow creates ripples which increases the surface area meaning that more oxygen is in contact with the waters surface.
> ...


Thanks Mark, I uploaded a quick video of my airstone in action. Is this good or bad?https://youtube.com/shorts/56Co03SwbDw?feature=share


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## dw1305 (12 Apr 2021)

Hi all, 


christinecrites said:


> My understanding is that it’s not the oxygen bubbles being released in the water but about them breaking at the surface to create a gaseous exchange.


It is a bit of both really.


Nick potts said:


> Having it lower can have benefits, as the bubbles are pulled up through the water column they create flow, and mix the water lower down with the surface layers.


I'd agree lower is better. The best of all is really an <"air-lift tube">. 

cheers Darrel


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## Nick potts (12 Apr 2021)

christinecrites said:


> I uploaded a quick video of my airstone in action. Is this good or bad?https://youtube.com/shorts/56Co03SwbDw?feature=share



That's a very fine mist, much like co2 bubbles.

I don't know how effective they would be at dissolving into the water like co2 does, but imo with air stones, you want larger bubbles, they create more lift and also more surface agitation.


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## christinecrites (12 Apr 2021)

dw1305 said:


> Hi all,
> 
> It is a bit of both really.
> 
> ...


Thanks Darrel! I’m going to look into an air lift tube!


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## X3NiTH (12 Apr 2021)

The smaller the volume of the bubble the larger the surface area for gas exchange is. Lots and lots of tiny bubbles will increase the air water surface area way beyond what the surface area of the tank actually is.

This makes lime wood air stones very effective for oxygenation when they are brand new, super fine bubbles. Using pressurised air through a CO2 atomiser is just as effective as the lime wood but without the issue of it wearing out as quickly as the wood and subsequently increasing the bubble size.


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## dw1305 (12 Apr 2021)

Hi all,


X3NiTH said:


> The smaller the volume of the bubble the larger the surface area for gas exchange is. Lots and lots of tiny bubbles will increase the air water surface area way beyond what the surface area of the tank actually is.


Yes, that is the one. 


dw1305 said:


> If you are reliant on direct aeration, you need either a lot of very small bubbles with a long residence time, or significant surface turbulence.


You get longer residence time with smaller bubbles as well. @christinecrites have a look at <"Aeration and oxygenation....">. I wrote it for specifically for <"L number keepers">, but it is relevant to nearly all fish keeping.

cheers Darrel


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## christinecrites (12 Apr 2021)

X3NiTH said:


> The smaller the volume of the bubble the larger the surface area for gas exchange is. Lots and lots of tiny bubbles will increase the air water surface area way beyond what the surface area of the tank actually is.
> 
> This makes lime wood air stones very effective for oxygenation when they are brand new, super fine bubbles. Using pressurised air through a CO2 atomiser is just as effective as the lime wood but without the issue of it wearing out as quickly as the wood and subsequently increasing the bubble size.


Ok, I’m pulling my ‘blonde card’ as I’m starting to get confused.... Do I want big bubbles or small bubbles? I thought it was about the bubbles bursting at the surface and not so much the size of the bubbles? I wanted tiny bubbles so it wouldn’t create additional current under the water that my betta couldn’t handle...


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## christinecrites (12 Apr 2021)

dw1305 said:


> Hi all,
> 
> Yes, that is the one.
> 
> ...


Ahhhh this is a great source of info. I will definitely need to finish reading (I should be working lol) before changing anything.

Wow the rabbit hole 🕳 🐇 is deep and my interest and curiosity has me fast tracked down it!


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## X3NiTH (12 Apr 2021)

From one Blonde to another - your intuition is correct.

The Betta can handle low oxygenated water quite well as it can gulp air at the surface and use its Labyrinth organ to sequester extra oxygen.


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## castle (23 Apr 2021)

dw1305 said:


> .
> 
> *Air bubbles don’t contribute much oxygen to the water directly by diffusion.*



I was under the impression that tiny tiny bubbles defused entirely? If I get super tiny bubbles in the aquarium I could swear I can see them shrink away. (These are bubbles that don’t float straight to surface).


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## dw1305 (23 Apr 2021)

Hi all, 


castle said:


> I was under the impression that tiny tiny bubbles defused entirely? If I get super tiny bubbles in the aquarium I could swear I can see them shrink away. (These are bubbles that don’t float straight to surface).


Yes, they do. Tiny bubbles are the ones you want for complete dissolution. <"Residence time"> is the technical term.  If you get really <"small nano bubbles"> they can potentially remain in solution for a very long time period. 


dw1305 said:


> You get longer residence time with smaller bubbles as well. @christinecrites have a look at <"Aeration and oxygenation....">. I wrote it for specifically for <"L number keepers">, but it is relevant to nearly all fish keeping.



cheers Darrel


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## Andy Pierce (23 Apr 2021)

christinecrites said:


> dw1305 said:
> 
> 
> > Hi all,
> ...


I believe the air lift tube is the principle behind the substrate-based filtration of the Oase biOrb series of tanks (biOrb Aquariums).  I will say that it can work as your only source of water movement, but I'm not sure I'd call it optimal... Cleaning the algae out of the air-lift tube is also something you're signing up for if you get one.


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## X3NiTH (25 Apr 2021)

Andy Pierce said:


> Cleaning the algae out of the air-lift tube is also something you're signing up for if you get one.



Swap it out for an opaque piece of PVC pipe of the same diameter, algae problem solved!


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