Rules Regarding Chemistry Controllers – Over-calibrating a Controller

Many years ago I received a call from a client telling me to come and remove a controller we had sold them because it would not even track pH correctly, let alone ORP. I suggested to the client that I come out with one of my people and do a couple tests before we removed the controller. When I arrived I took 2 commercial test kits, asked him to grab one of his people with test kits and we would take 4 pH tests in different parts of the pool and compare notes.

When we compared our readings we had 3 quite different readings, so I asked him which one he wanted to use; this quieted him down enough for me to explain to him that when the pH reading he took was different from the controller, the worst action he could take would be to automatically calibrate the controller to his hand reading, not only would it cause the controller to not track the pH correctly but due to the inverse relationship pH holds with ORP, it would likely cause the chlorine to be out of desired range.

Here are a couple “Road Rules” regarding chemistry controllers:

  • If you have to calibrate pH, calibrate it 1/2 way between the reading you took and the displayed reading
  • Do not calibrate ORP, change the set point! In fact our new Net Connected controllers will NOT let the Operator calibrate ORP, just move set points, and that is a good thing.
  • If you need any help with your controller, please feel free to give us a call : 800-818-8266