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Help Understanding Air Stones

christinecrites

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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?
 

Mark Nicholls

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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

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

dw1305

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Hi all,
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.
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
 

Nick potts

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X3NiTH

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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.

:)
 

dw1305

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Hi all,
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.
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
 

christinecrites

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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...
 

christinecrites

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Hi all,

Yes, that is the one.

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
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!
 

dw1305

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Hi all,
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.
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
 

Andy Pierce

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Hi all,

It is a bit of both really.

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

cheers Darrel

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