The lights turn on and off in sets of three to "simulate" dawn and dusk. The first set of three come on at 7:00am, and all lights are running by 9:00am. All lights run until 5:00pm, then the first set turns off at that time, and all lights are off by 6:00pm. This is kind of temporary....I will be gradually increasing that over the coming months to have the lights come on a bit later in the morning, perhaps 8:00am or 8:30am, and run until about 9:30pm.
I do not use a pH controller, nor do I perform any direct testing of the water parameters either. Observation of any problems or issues is enough info for me to act upon.
The CO2 comes on at about 8:15am right now, and turns off at about 5:15pm. I've found nothing to indicate that turning the CO2 off or leaving it on has any additional benefit OR deleterious effect after the lights turn off. I don't believe that turning it on prior to the lighting has any additional benefit either. I've tried, but I just don't see how it does anything except waste CO2.