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Where do you put your intank CO2 diffuser?

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41K views 7 replies 4 participants last post by  chicken.nublet  
#1 ·
Hello all!

Just set up my CO2 system for my little cube tank and I'm just wondering where I should be placing the diffuser. In case it matters, it's the small neo diffuser.

I've placed the diffuser opposite the outflow of my HOB filter because I've heard that the outflow will push the bubbles around. Unfortunately I don't think my HOB placement is optimal, I'd love to hang the filter on the side so that the current pushes at the plants but the light is too big for that, if you can understand what I'm trying to say. I could place the light the other way but eh, for some reason I'm not really inclined to do that... Here's a picture of the tank so you have an idea of where the filter is. I took this before I got the CO2 sorted out so the diffuser isn't in the picture.



The bubbles are being pushed around a fair bit, but it doesn't really look even and in any case the plants that need the CO2 the most, the stems on the right, don't seem to be getting much of the bubbles. I was thinking if perhaps I should put the diffuser where the stems are planted so that they get most of the CO2 and as the bubbles float up, they will get to the outflow eventually and get pushed to the rest of the tank. Appreciate if anyone could give me a bit of advice on this or if the current placement will be fine. Cheers!
 
#2 ·
In an ideal scenario, none of the bubbles would make it to the top of the water. This ensures that the CO2 is being fully dissolved into the water.

However, since that is not happening, you can try experimenting with the placement of the diffuser. My inclination would be to leave it under the outflow of the HOB filter, since the flow will push the bubbles down, hopefully giving them more time to dissolve.

Counterintuitively, if you place them near the plants (on the right), the bubbles may simply rise to the top, wasting some CO2.
 
#6 ·
sudhirr said:
Most tutorials and pro tip vids show the placement of diffuser as close to the substrate usually in the front portion of the tank. The placement is also due to the fact that most planted tanks have a gradient from back to front.

Check this post https://youtu.be/oyq0GlXKuCA
Click to expand...
GrampsGrunge said:
The optimum setup would be near the substrate, opposite the input for a canister filter so the water coming across the tank hits the front glass and diffuses downward in a semi chaotic fashion.


HOB filters tend to have inflows that angle downwards, and depending on the strength and depth of the water at the lip of the return "chute" of the HOB filter, there might be enough flow across the top of the water to force the slowly diffusing CO2 bubbles to move downward and outwards, once these bubbles get to the "mist" size it doesn't take much current to divert them from their trip upwards to the water surface.


Maybe place the diffuser off the side of the HOB inflow on the back glass so the CO2 bubbles can be naturally caught be the inflow and spread around more?
Click to expand...
Thank you both. I've got my diffuser as close to the substrate as possible. I might try positioning the diffuser closer to the intake as suggested... but wouldn't most of the bubbles get sucked into the filter as a result?
 
#5 ·
The optimum setup would be near the substrate, opposite the input for a canister filter so the water coming across the tank hits the front glass and diffuses downward in a semi chaotic fashion.


HOB filters tend to have inflows that angle downwards, and depending on the strength and depth of the water at the lip of the return "chute" of the HOB filter, there might be enough flow across the top of the water to force the slowly diffusing CO2 bubbles to move downward and outwards, once these bubbles get to the "mist" size it doesn't take much current to divert them from their trip upwards to the water surface.


Maybe place the diffuser off the side of the HOB inflow on the back glass so the CO2 bubbles can be naturally caught be the inflow and spread around more?
 
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