Salt pools contain a salt water chlorine generator which breaks down the salt into sodium hydroxide and hypochlorous acid. This causes the ph level to rise, which is then adjusted using muriatic acid. The reduction in ph turns these chemicals back into salt to start the process over again.
You are still responsible to check and maintain free chlorine, ph, alkalinity, calcium hardness and cyanuric acid levels.
Over time, additional salt will need to be added to compensate for backwashing, splashing and winterization.