very cool!

If I am correct, the bottom of the "air gap" is open? This is where the CO2 dissolves into the airgap, right?

The only thing I do not like is that it is yet another internal device. So we have the internal CO2 venturi device, powerheads connected to CO2 lines and now another internal device. Get's very hard to hide all these devices.
Could it be possible to make an external design? p.e. with a very big air gap (tube) that enables you to put the pH-electrode outside the aquarium? Think it will increase the reaction time and possibly less accurate.

well, I think it is very very wise and happening! a major breakthough in the hobby!

greets,

yme