A cycles of concentration (COC) control process and system for an evaporative media cooling system having a water storage tank in fluid communication with a drain valve and a refill valve is disclosed. In one step, the COC control process includes the step of executing a plurality of discrete refill events to maintain a level or volume of water within the storage tank. In another step, the COC control process includes the step of executing a discrete drain event, equaling the volume of a refill event, after a discrete refill event has been executed when necessary to maintain a target cycles of concentration value of the water within the storage tank. In one embodiment, a discrete drain event is executed when the number of refill events is greater than or equals a target cycles of concentration of the water in the storage tank.