From the Jandy Manual:
4.6.2 What Type of Salt to Use • The purer the salt, the better the life and performance of the electrolytic cell. Use a salt that is at least 99.8% pure NaCl. The salt is an evaporated, granulated, food quality, non-iodized salt. Consult your salt supplier. • Avoid using salt with anti-caking agents (sodium ferrocyanide, also known as YPS or yellow prussiate of soda) that could cause some discoloration of fi ttings and surface fi nishes in pool. • Water conditioning salt pellets are compressed forms of evaporated salt and may be used but will take longer to dissolve. • Do not use calcium chloride as a source of salt. Use sodium chloride only. • Do not use rock salt because insoluble impurities mixed with the rock salt can shorten the life of the unit. 4.6.3 How Much Salt to Use Use salinity test strips, a TDS/salinity meter, or another reliable method to test the salinity of the pool water. Once the existing salinity has been established, use Table 1 to determine the amount of salt to add to reach the desired level. Be conservative when adding salt as it is easier to add more if needed than it is to dilute if there is too much salt.
• 4,000 ppm of salt is recommended for optimum water conditions.
NOTE In cooler water conditions (less than 65°F), it may be necessary to add more than 4,500 ppm of salt to keep the “Check Salt” alarm from appearing on the power pack.
• Low salt concentration below 3,000 ppm will cause premature cell failure. • High salt concentration above 6,000 ppm may cause corrosion damage to pool fi xtures.