calcium reactor with controller setup

I'm setting up a Coralife CA+ reactor with a Pinpoint Ph controller. the CO2 solenoid is plugged into the 1st controller outlet to lower the Ph when above setpoint, but the part I can't figure out is if the water circulation throguh the reactor should be laways on, or if it should be plugged into the 2nd controller outlet to only recirculate when the Ph drops below setpoint. Probably something obvious here but I'm missin' it.

 

not sure what method you ae using but connect the Solenoid valve to a pH controller and place the pH probe into the calcium reactor. The set point valve 6.5 to 6.7. then switches the CO2 on and off to maintain a target pH within the reactor to then the other side probe pH probe is placed in the tank, and switches on the CO2 flow to the calcium reactor only when the pH in the tank has dropped too low like 7.9 or 8.0 then that kicks the reactor back on I have never messed with a Coralife unit so I'm not totally sure about your set up.. If you can post the PH controller unit and model maybe I or someone can tell you more about the way it works I am assuming you use a solenoid valve on the CO'2 tank ?