CTBYREG - Returns the CT Required for Inactivation of Giardia Cysts for a given Temperature, pH, and Chlorine Residual using the Guy Schott regression formulas. This formula is used in some California Drinking Water reports and in certain cases may be used instead of the CT function which uses the CT tables.
CTBYREG(Temp, pH, Cl2)
Temperature – Water Temperature in Deg C
pH – pH of the water (only required for Inactivation of Giardia by Free Chlorine)
Cl2 – Chlorine Residual at end of disinfection segment in mg/L. Only used for Inactivation of Giardia by Free Chlorine, for all other lookups use -1 to indicate not used.
=CTBYREG(9.6,7.6,1.54) returns 50.75