zeebo

Hi,

I am a little unsure about this matter.
I am aware that water movement in tanks create more oxygen.

My question is the water movement in the tank, does it have to break the water surface (usually very noisy) or it can be beneath the water surface?

Chief_waterchanger

The reason breaking the surface gives more gaseous exchange is because for the split second that the water surface is broken there is more surface area. Think about a bubble, much more surface space on the bubble as a whole than on the amount of water the bubble is sitting on. That is the basic idea. There is a scientific principle that says gases will try to equal themselves out in adjacent objects. http://en.wikipedia.org/wiki/Diffusion

So the more surface area = more area for diffusion to occur. So I would say that it would need to break the surface, but then again Dino could probably provide a better answer, being that he has a science degree and all.

Neville

How can u move the water beneath the surface zeebo? the water surface will move eventually, the point is u can't move water without moving the water surface, put airstones, toys or whatever, ultimately the water surface will move, it's not that noisy !

zeebo

Thanks Chief.

Gargoyle

I have nothing breaking the surface at this point. I do have a ripple effect going on all the time from the output of the 2 filters I have.

I have been wondering about this for a while as well... I believe exchange is taking place because my fish are still alive but I still wonder about it..

zeebo

Hi Gargoyle,

Yeah I know what u mean about wondering on the subject.

I used to break the water surface but the splashing against the glass panel at the top of my tank is really noisy as my pump is powerful. All that splashing is loud. We can actually hear it from upstairs.

Eventually I extended the pipe further down away from the water surface. It does not break the water surface now.

I do want to do the best for my fishes. Benn thinking of a way to resolve this.

So I added a separate powerful air pump into the tank. Turn it on every now and then in a day to break the water surface. It is so much quieter and it is actually quite beautiful to see a ga-zillion bubbles go up and break the water surface. I might put it on a timer when I am traveling.

Thanks for sharing your thoughts.

Butterfly

When the water is rippling it is moving water from the bottom of the tank to the top. This causes the area of highest concentration to equalize with the area of least concentration. This happens with CO2 as well as oxygen.
So if the air surrounding the tank has more oxygen and CO2 than is in the tank just the surface movement will help the tank water absorb oxygen and CO2 from the air.
It won't be a huge amount but some of each will absorbed. This is called diffusion. Diffusion is - the movement of material from a higher concentration to an area of a lower concentration.
Now if a tank is running CO2 you wouldn't want surface movement at all because then the Co2 would out gas because the concentration is greater in the tank than in the air and the equalization effect would again be happening. Again diffusion but going the other way.
Carol

zeebo

Thanks Butterfly.

CatladyDane

Regarding the noise thing, I have two tanks. In the 10g I have a small bubble wall. The tiny bubbles break the surface almost silently. In the 20g, the very large bubbles from the bubbling decoration are comparatively noisy. I also discovered that the greater the distance from the top of the water to the filter output, the louder the waterfall effect is.

zeebo

Hi CatladyDane,

Thanks for sharing.