Once you add the initial amount of salt to reach the required concentration (For example, Jandy requires 3,000 ppm salt), you only have to add salt to replace what is lost to water loss from sources such as splash-out and backwashing. You should monitor the salt level as reported by your unit and test the water periodically to verify. The amount needed per month should not be much at all.
To raise the salt level by 3,000 ppm in 40,000 gallons, you would add 1,000 pounds of salt. Your water will already contain some salt, so you will subtract the existing amount to determine the amount to add.
What is the make and model of your salt water chlorine generator?
Great info, thanks a lot. I will check out exactly what model generator it is and post later. I know it's a Jandy and a model that just came out.
Monte