In certain parts of the world seawater has become the makeup water of choice for evaporative cooling water systems. The use of seawater is generally limited by the ability to control scaling of mineral deposits. To address the need for more effective deposit control and the ability to operate at higher cycles of concentration, scale inhibitors were evaluated under evaporative conditions that simulated the operation of a cooling water system. This permitted both the evaluation of the hydraulic operation and the relative efficacy of specific scale inhibitors. Laboratory studies demonstrated that the selection of specific chemistry for scale and deposit control could materialize in operation of seawater cooling systems at higher concentration factors than is normal practice, and potentially reduce or eliminate the use of acid for pH reduction.