Thanks for joining in Vinny.
I have tried that function, but it doesnt work for my setup.

If i set nominal pH to 6.5 and deviation to 0.5 it would work fine in the daytime when co2 supply is on.
But in night time when co2 is off the pH will gradually in 45-60minutes after co2 is off rise to tank pH, around 8-8.3.
It will then give an alarm even in this normal condition, since it's outside nominal value.