After the initial dosage of salt, you will only need to add salt when necessary. The most commonways salt is lost is through leaks, rainwater overflow, filter backwashing, and bather splashout/carry out. Normal water evaporation does not lose salt, it increases the concentration. Themake up water added to bring the water level back to normal will then reduce the saltconcentration back to 3,000 ppm.The Digital and Soft Touch units both have low salt indicators, with the Digital going further toprovide the proper salt amount needed to restablish 3,000 ppm (based upon the programmedpool volume input).