the pH controller/monitor is really only necessary when you have VERY soft water (a low
Kh level), where the pH might drop too quickly and harm sensitive fish (like discus for example).
I'm assuming you're going with the Milwaukee
CO2 regulator, so that you've got a solenoid valve to plug into the controller if you get it?
Even if your water is a little soft, you can plug the solenoid valve into a regular lamp timer, and just have it turn on an hour before lights turn on, and off when the lights turn off.
If your water is moderately hard, you an run
CO2 24/7. You'll see maybe a .2 change in pH overnight at the most, and this won't bother fish at all. The only downside is you'll use a little more
CO2 than necessary, but at $10-$15 a 5/10lb fill, that'll last you months and months...its worth it.
Because yes, a steady bubble rate should give you a steady
CO2 level in the tank and a pretty stable pH. Only those with a
dKh under 4 should be concerned about pH issues.