if you re talking rdwc i usually float it around a set point 5.8 -6.3 is what range I used , not sure if it was correct seemed to work ok during each nutrient cycle.

right now I set it at the set point and it feeds it's self, always the same pH or the one I am targeting. I think my bucket I will go for a start pH and wait until it rises or falls. but I think it will self regulate in that when it's time to freshen it it will also be ready for a pH adjustment