[tmz]

IMHO pH is over-complicated by people in this hobby. Someone with a more formal chemistry background will shoot me for this, but think of it as a ratio between CO2 and alkalinity. You can change the pH by altering either side of the ratio.

Every reef tank should be maintained to a specific alkalinity. So, in essence, that side of the ratio should be fixed. If you are doing a good job at maintaining alkalinity, and you still have "pH problems," it essentially means you have a CO2 problem.

I agree,excess CO2 depresses ph and thinking of it as a ratio between CO2 and alkalinty is a good way to go.U
Understanding how CO2 adds to H is optional.
Keeping alkalinity constant is very important particularly so with more sensitive corals like sps, in my experience. More so than ph as long as ph remains in an acceptable range( 7.8 to 8.5) So, using alkalinity supplements to manage ph is a poor way to do it since they add alkalinity and any bump in ph may be short lived effect since CO2 flows back in with the air and biological processes.
A scrubber does not effect alkalinity and provides air with low CO2 continuously.

Maintaining higher ph may lower alkalinity to some extent since both biotic( skeletal growth) and abiotic( white solids on heaters pumps etc.)precipitation occur more easily at higher ph resulting in more carbonate alkalinity being used over time.