pH Control

I am trying to set up pH control with the Profilux 4 using CO2. I am only interested in lowering the pH. The current setup has a solenoid that activates when the pH gets too high. The logic is set up as a cycle but this method overshoots and too much CO2 is added, dropping the CO2 too low.

I can possibly add a regulator to the CO2 to lower the amount coming in, however, this is added cost. Could this be changed in the logic to have the solenoid open for 3 seconds and then stay closed for 30 seconds to a minute before it opens again?

Combine a timer with PH control via programmable logic

Set the valve socket to Programmable Logic 1
Logic 1 on the function and
Control inputs on timer 1 and PH depreciation

You set Timer 1 to the on/off variant with appropriate time regulations.