Air in calcium reactor

[Delphinus]

What I mean by recirc line is a secondary line, usually 1/4", that can bring the gas bubble into the pump intake. The pipe that carries most of the water is likely inset into the lid a little bit thus giving the gas bubble a place to form. The recirc line would have to be flush to the inside of the lid, or even recessed a little so that it's drawing from the absolute highest point in the reaction chamber thus mitigating the size of the bubble buildup.

I'm probably not explaining this well enough. I'll see if I can dig up some photos or diagrams.