Why I monitor pH.
1) Calcium reactor is controlled in part by pH; 6.70 or above co2 is injected to dissolve media.
2)If pH in dt goes too low Calcium reactor co2 is turned off
3)If pH in dt goes too low Sulfur reactor is turned off
4)If pH goes below 8.2 kalk drip is turned on.
5) Monitoring pH gives a general feeling of how the tank is doing, if pH is "out of range" one can look for a problem?
There is always a parameter that someone will find “useless”. I hear reefers say all the time “I don’t test for that and my tank is great”; whether it’s pH, no3, po4, etc. With pH being so easy to monitor, I say why not monitor it? pH is more info we can use to make our reefs better.