Try below, amend if wrong. Cheers
1. Calcium Carbonate Media
2. Flow (CR inlet/Water from Aquarium)
3. Prefilter/Surfur reactor
4. CO2 Tank/Cylinder
5. Regulator (Operation pressure/Cylinder pressure) with Solenoid valve
6. CO2 Supply with bubble counter
7. PH Controller
8. Flow (CR outlet/effluent from reactor)
9. PH Probe
Cheers and Happy Reefing..