âtreat pH swings as a diagnostic signalâ is exactly my philosophy. Particularly direction and very important is the Rate of Change (ROC).
@Reikox is right in that âmostâ nutes lower pH, and plants eating will raise the pH, but that is not the only thing that could affect pH. For example I have been considering a Dyngro product call Protext, which absolutely raises pH. I have seen pH drift down in my own tent on occasion. I would be afraid to assume that the only pH impact was from plants eating. I believe that DO also affects pH.
Take my last res change as an example. I was having pH swings of 1.0 in less than 24 hours. It went from 5.5 to 6.5 in 20 hours. Had I been controlling pH with a dosing pump, the pH would have stayed at 5.5 â 5.6 and I never would have been aware of, what I suspect was nute imbalance, until the pH Down bottle went dry.
Automating the pH would have disguised this event.
Now, I suspect that I could extrapolate the ROC by looking at the frequency and volume of pH adjustments, and possibly program the logic for a ROC alarm.
If I ever automate the rez chemistry I would need to somehow make unrealistic ROCs visible.