I have the old version of an 818. Basically the same, just larger.
10 gallon Co2 tank.
Dual Smith Gauges
Milwaukee MC122 Ph controller, MA 955 solenoid. This is only used to shut off the gas if Ph in the reactor drops below 6.3
Needle valve and glass bubble counter. Unknown make. I dont use the Geo's bubble counter to count bubbles. The gas does pass thru it.
Reborn calcium media.
ZEOmag = 8% of the reborn media.
For tuning you want to start the effluent ouput to be a slow stream. Just past the fast drip rate. Then you set the bubble rate. What you are shooting for is an effluent 15 to 25 dKh. Depends on what corals are in your tank.
Once you get to that then you can either cut the bubble and Co2 rate, or up them both. depending on what your tank numbers are.