The primary difference between salt water and chlorine pools is the mechanism used to clean the pool water. Both types of pool use chlorine to kill bacteria and algae, but in salt water pools this chlorine is produced using a generator. Fresh water chlorine pools do not generate chlorine; owners must dissolve chlorine in the water to kill unwanted organisms.
Salt water pools generate chlorine through electrolysis. The salt water passes over a chlorine generator cell, which produces the chlorine. While the pool owner does not add chlorine to a salt water pool, the proper salt balance must be maintained. The salt is not used up by the chlorine generation process, but it is diluted by rain and washed away when water is lost. Periodically replenishing this lost salt maintains the correct chemical balance.
Salt water pools have a higher up-front cost than fresh water chlorine pools due to the expense of installing the generator but lower costs over time. They require less maintenance, and periodically replenishing the salt is less expensive than regularly replenishing the chlorine. The most important maintenance task for a chlorine generator is ensuring that calcium and other minerals do not build up on the generator cell.