Sponge Filter Mod To Allow Inline Co2 Dispersal


Oct 3, 2017
In my two Dennerle 10g’s I have always used GLA atomic diffusers as well as Dennerle Eckfilters.
These are both shrimp tanks containing BKK, Blue Bolts, & various neocaridinas, which is irrelevant...

I find that cleaning the Dennerle Eckfilters can be quite a pain in the butt, also it’s lack of biofiltration after cleanings.

I use sponge filters in my other shrimp tanks but because these two tanks run CO2 I have chosen not to have an air pump running all day (only when the lights are off).

I have made a few changes to a sponge filter thinking that maybe I can figure out a way around this problem.

I’ve attached a small submersible pump to the top of the sponge filter to avoid using the air pump. Where the air tubing would normally attach I was thinking about hooking my CO2 line.

I am very hopeful that this might help CO2 dissolve better into the water column after running through the submersible pump.

Does anyone know if I will be able to get away with this setup without having to use any type of diffuser INSIDE of the sponge filters tubing, or if this will be safe to run?

I have considered that I possibly might need to make some type of spray bar and have the CO2 line come in at the base of the bar where it meets the pump so that I do not have air bubbles running through the pump if it turns out that it could be damaging it.

CDA Enterprises

Sent from my iPhone using Tapatalk


Micros Spiller
Feb 16, 2015
Think it has potential. One thing I can tell you is if the co2 is hitting the pump one big bubble at a time, you're gonna hear a distinct chirp every time a bubble hits the prop. If you could somehow pre-diffuse the co2 instead of having an open line, you'd get a steady sizzle sound that is much more pleasant and lower volume. Also it would greatly help the diffusion because the impeller would be working against many small bubbles instead of one big one after another, which means a finer mist exiting the powerhead.

A piece of regular cotton ball stuffed tightly into the co2 line works pretty good without increasing the diameter much. Of course you cant do this using the current nipple connection


As for how to insert it into the intake tube, well, it wouldn't be as sexy as what you have now, but I used to drill a hole in the side of Aquaclear pipes and stick it in there


Having said all that, I think the design you have is worth trying out first. If the co2 is somehow separated into smaller bubbles, like the air bubbles appear to be, it might work OK like it is.

Id be interested to see how it goes


Super Moderator
Staff member
Lifetime Member
Jun 20, 2016
It will work. I like using internal filters from Aqua El for pretty much the same reasons. They already have the place to connect the air/CO2 after the motor to get good distribution without affecting the propeller.

For a 10g it might be a little under powered but if you can work with less than 30mg/L CO2 then you are good to go.