While I was refilling my 2nd CO2 canister, I left my Neo diffuser in my tank for a few days unused. When I hooked the CO2 back up, the Neo diffuser stopped working (no bubbles) and soaking in bleach didn't help. Odd. I had to replace it with a new one with worked fine.
Anyway, since I was messing about in the unsightly rear corner of the tank (the R. Macandra do a good job obscuring the mess), I decided to position the new diffuser under my external USB pump. The USB pump sucks up the bubbles and seems to be doing a good job pushing the CO2 across the substrate ... no visible bubbles float to the surface, as long as the diffuser is set at 1 bps. When I increase the CO2 to say, triple the amount at 3bps, the pump occasionally makes gurgling sounds (gas trapped in the pump) and I see bubbles being spit out and floating to the surface.
Heres a video of the concept. From the video I also notice that there are CO2 bubbles from my Lily Pipe output already being pushed to the corner substrate level which is good, so this extra diffuser is just to add a little more to the substrate level.
p.s. the orange lava chips were from 10 years ago. I wanted to create a slope at the back and a bag of this was a whole lot cheaper than aquasoil. So I put it right at the bottom, but after 10 years, they have made it to the surface.... I try to remove any that are visible from the front
pps I have never cleaned the twinstar and the area around the metal mesh disc remains a very clean white though other parts have algae.