A method for controlling a cooling water tower comprising: providing a cooling tower system, which includes a recirculated evaporative cooling water stream, a source of make-up water, an evaporative cooling unit, a heat exchanger, a bleed off line, and a bleed-off valve which is in communication with said bleed-off line; providing a plurality of conduits through which said makeup water flows into said evaporative cooling water stream, wherein there is at least a first conduit that contains a weak acid cation ion exchange column and a second conduit that does not contain a weak acid ion exchange column, and wherein each conduit has at least one conduit valve; choosing a pH and a conductivity setpoint value and a deadband value above and below said setpoint value in said cooling tower system; measuring both the pH of said evaporative cooling water stream with one or more pH meters and conductivity of said evaporative cooling water stream with one or more conductivity meters; and implementing a response to said conductivity measurements and pH measurements is disclosed.