First Tank: CO2 Diffusion Question

[Stitchwod]

Hi,

I'm currently only a couple of weeks into my first tank, so please be gentle.

Firstly I have a Juwel Rio 400 tank (125g) with internal filter system. Due to this I decided to go with pressurised CO2 with a large ceramic diffuser (50mm). In a future tank when I have an external filter system, I will probably go with an inline setup for optimal diffusion, but this isn't possible at the moment.

The CO2 is running at approximately 3 to 4 bps and the drop checker is showing a nice lime green colour - identical, or perhaps a little more lighter green, than the reference. This drop checker is about 1.3m away from the diffuser. It take a while to change but never goes yellow.

Everything appears ok but my question is more about diffusion/spread of the CO2.

The diffuser is directly below the outflow of the filter and this helps blow the tiny bubbles around the tank. The trouble is the bubbles are mainly along the back wall of the tank. The majority slowly rise to the surface and seem to disappear rather than circling the whole tank.

I've tried to make a video to help explain the issue:
http://youtu.be/zJIUUulEADE
I understand it's hard to see on the video but there is a large cloud of tiny bubbles along the back wall but not very many at the front.

Is this a problem for the front plants? Will they not be getting enough CO2? Or do the tiny bubbles actually dissolve into the water and then this water will circulate the tank?

Sorry, I've searched and read many posts but can't seem to find an answer.

[Complexity]

The video is set to private so we can't see it.

Have you tried moving your drop checker to different locations to see if it still shows yellow in those areas?

[Stitchwod]

Just updated the link.

YouTube appears to have compressed the video so the quality isn't great.

Haven't moved the drop checker yet but it's as far away from the diffuser as I can get it (on the back glass).

Do you mean move it to the front glass and see if it turns blue?

[Complexity]

Originally Posted by Stitchwod

Do you mean move it to the front glass and see if it turns blue?

Yes. Move it to any place that you're concerned isn't getting enough CO2. Give it a few hours and see what happens. Or if you really want to be sure, pull the drop checker out and let it turn blue and then put it on the front glass to see if it turns yellow.

[Stitchwod]

Sure, will give that a go over the next few days. Thanks

Do the tiny CO2 bubbles fully dissolve into water? Or do they remain visable?

[Complexity]

Well, that's kind of an answer onto itself. If the bubbles are visible, then they're not dissolved into the water so they stay visible. When they dissolve into the water, they are no longer visible.

When you get a canister on your tank, you can switch to using a reactor which holds the bubbles inside the reactor until they're fully mixed with the water. Then only the CO2 that's dissolved with the water gets into your tank and you never see the bubbles. I think it's less wasteful, but CO2 is cheap. So it's mainly a matter of getting rid of what some call the 7-Up look (named after the soda).