I believe you mean pH controller to control the CO2. Yes, it is ok to use a timer as that is how I set up my controller. My pH controller is set to shut off at 8 pm when the lights also go off. It stays off untill 8 am. This gives the CO2 a 2 hour head start before the lights come on at 10 am. Your pH may climb as high as 7.00 to 7.30 until the CO2 system kicks in. This will not cause a problem unless your CO2 is a non-pressurize system. Then it would take too long to get your Ph back down to 6.00.
Using a timer will prevent CO2 waste as plants have no need for it when photosynthesis stops. I also would recommend you set up a power head for overnight surface agitation to provide more oxygen, because during the day, only the biofilter and the fish compete for it. With the added demands for oxygen by the plants at night creates more competitation. What is your current pH in the morning before lights turn on?
- - - Updated - - -
I believe you mean pH controller to control the CO2. Yes, it is ok to use a timer as that is how I set up my controller. My pH controller is set to shut off at 8 pm when the lights also go off. It stays off untill 8 am. This gives the CO2 a 2 hour head start before the lights come on at 10 am. Your pH may climb as high as 7.00 to 7.30 until the CO2 system kicks in. This will not cause a problem unless your CO2 is a non-pressurize system. Then it would take too long to get your Ph back down to 6.00.
Using a timer will prevent CO2 waste as plants have no need for it when photosynthesis stops. I also would recommend you set up a power head for overnight surface agitation to provide more oxygen, because during the day, only the biofilter and the fish compete for it. With the added demands for oxygen by the plants at night creates more competitation. What is your current pH in the morning before lights turn on?