One of the neat things about having a controller is it's ability to continually monitor level's of your choosing in the system. It also allows you to "Graph" the results to see the cycle of when your ATO is topping off, temperature fluctuations and my question of the day, the cycle of pH.
I've noticed that my pH, according to the monitor reaches a peak around 10pm and it's low point at around 10am. It can be plus or minus a half hour, but graph is a consistent zig, zag between the two times.
Why? I've searched the forum, and maybe I'm missing it, but I haven't found a clear explanation. My main lights don't kick on until around 10am, so that's my guess, but I'd be interested to know any information.