Going to reveal my hand here, as I have not got round to building "my idea" but Zeus's activity on CO2 dissolution reminded me. This is what the extra relay output "CO2 Pump" was for on my PLC controller, in 2016 but not ever got round to it
🙁.
Basically CO2 doesn't dissolve very fast in water, so what all these reactors, injectors etc all try and do is prolong the contact time between CO2 bubbles and the water.
So you get a length of pipe and pass the water and injected CO2 along it, allowing time for the CO2 to dissolve. You will probably need to put smaller diameter tubing in the big tubing, to stop the CO2 forming a big bubble.
So picture below shows a pump pumping water via a CO2 injector, then into a coil of tubing, say 2-3 meters, filled with smaller diameter tubes.
View attachment 119258
Use this calculator to see how many smaller pipes you can get in a bigger pipe. In my picture I have 7 off 5mm pipes (outside diameter) inserted in a 16mm (inside diameter) pipe.
https://www.engineeringtoolbox.com/smaller-circles-in-larger-circle-d_1849.html
This reduces the cross sectional area from 200mm2 (16mm) to 113mm2, which is nearly the same as 12mm2 tube, so you could get away with a 12mm2 pump. A valve to regulate flow before going into the tank might be helpful to slow the flow as well.
So Zeus, throw your reactors in the bin and use PVC tubing.
🙄
Oh, not tested this idea, but I bet Zeus is up to the task.
😀