Applied cooling water chemical treatments are often accepted as the end-of-all and the cure-for-all system problems. In fact, environmentally accepted and safe-to-management cooling water treatments tend to not perform up to expectations without continuing tweaking. Furthermore, that which is tweaked must fit the cooling water chemistry, the system's needs and often the system's discharge needs. This manuscript specifically provides insight as to how to adjust for success those multiplicities of variables, which affect evaporative cooling water systems. Tweaking, acting for success, includes balancing the interactions among pH's, flow, temperatures, deposit biofouling, scales, chemistry, operation, etc.