[Scouter]

I tried something similar. I put my DIY CO2 end tube into the sponge of my powerhead. The theory was that the bubbles would be trapped in the sponge and slowly dissolve in the moving water. Unfortunately, the bubbles collect and leave the sponge in large "glugs." It did work for me though because I had a powerhead to suck up most of the bubbles before they could leave the sponge.

Going off of this experience, I'm not too sure it'll work, but my last theory turned out to be bogus so who knows. Good luck.

Scouter

 

[Scouter]

I'm not entirely sure what you mean by compact-if you mean fine holes then yes. The sponge I used was cut from mattress foam you can get at Joannes and other fabric stores. I froze it in water and drilled a smaller hole for a good fit and after thawing, stuck the CO2 tubing up the sponge. Sorry I can't offer additional help. Good luck though- and let us know if you can get it to work.

Scouter