I have a question about PH controllers and CO2.

[ksmith]

I am new to planted aquariums, although I have been in the aquarium hobby for decades, so I hope this doesn’t sound like too strange of a question.
I have a 38 gallon tank that I would like to grow live plants in. I have already purchased everything such as; Flourite gravel, 5lb CO2 tank, regulator with solenoid valve, bubble counter, drop checker, glass ceramic diffuser and lights.
One of the reasons that I am looking into a PH controller is because my light system has a 24\7 timer built in. It is a “Finnex Planted+ 24/7 led automated light fixture”, https://www.youtube.com/watch?v=Jq7rPYzTIMM , which slowly turns the lights on throughout the day and ends with it looking like a sunset and into a moon glow. Because of this I thought it would be easier to have a PH controller to deal with the different lighting effects throughout the day.
My tank tends to run on the high side with PH. Ideally I would like to have it at 7.0, but because my tap water is closer to 7.8, I am always trying to adjust it by adding buffers after water changes.
This is where my question comes in. If I set the PH controller to 7.0 – 7.2 and the PH is running higher than that, when the lights are dimming down or off, isn’t the PH controller going to keep running to adjust the PH even if the lights are off, and if that happens wouldn’t it cause an issue with having high levels of CO2 in the tank when the lights are off.
Also, what if it is the opposite? Say the PH range is perfect during the day when the lights are on? What would cause the PH controller to kick on and make sure there is the right amount of CO2 in the tank when the plants are looking for it in a fully lighted tank?
Thank you for any suggestions you can give me. I am really excited about the idea of a beautifully planted tank.

 

[Delapool]

Hello, welcome to the forum

I run CO2 to come on an hour before the lights. Both the lights and the CO2 are on timers.

Once the CO2 is on then the PH controller will switch it off if PH drops below a certain level. And then back on when PH lifts back up.

In addition I've also found a bubble counter may be useful if you have one. This is because the diffuser may be able to only handle a certain maximum bubble count.

Also I find the bubble count might decrease slightly as the bottle empties so I usually check the bubble count per minute every several weeks or so.

Otherwise the ph controller does all the work - just set and check every so often.

As you mention I would be wary of running CO2 at night with the lights off.