The brine tank must constantly be at least 1/3 full to guarantee that your water softener has enough salt to function correctly. A decent rule of thumb when adding salt is to fill the tank halfway. That way there's a little room for error if you add it too soon or not enough if you wait too long.
Salt does not dissolve in water; it forms an ionic bond with the calcium and magnesium ions in your water softener resin. As these ions attach to the salt, they become part of its crystal structure and are removed from your drinking water. Over time this process removes these ions from your water softener, causing it to become less effective at removing other contaminants. Therefore, it is important to regularly flush your water softener to remove any salt that has dissolved into the resin.
Here at The Water Closet we recommend that customers use a half-strength salt solution to flush their water softeners. This will ensure that all the salt has been removed from the system while still maintaining a safe amount to not overload the garbage disposal or cause other problems with your plumbing system.
For best performance, maintain your brine tank at least one-quarter full of water softener salt at all times and no more than four to six inches below the tank's top. Maintain a salt level that is a few inches above the water level at all times. This will help prevent salt from being dumped during a water pressure loss.
The water in a household drinking water system is usually hard enough without adding any additional hardness such as calcium carbonate. However, if you have limestone rock in your basement, or other sources of calcium carbonate, then it would be beneficial to add these substances to the water supply. Limestone rock reduces the amount of chlorine needed to disinfect your water while still providing some degree of hardness. Chlorine is effective at removing bacteria and other organisms from your water supply, but it can also remove some of the calcium carbonate particles so they cannot react with other chemicals to form scale. Scale is an issue with any type of plumbing system because it forms on pipes, valves, and fixtures and can lead to increased pressures which may cause leaks or even break down piping work. Drinking water systems require special monitoring because contaminants can become trapped within the stone itself. Some areas allow up to 15 ppm of arsenic in drinking water, so do not use limestone to reduce arsenic levels.
A conventional water softener brine tank should always have water in it, except when it is being used to renew the water softener resin. To assist minimize salt bridging, some premium water softeners only add water to the brine tank 4 hours before the water softener regenerates. However, this additional step is not necessary for most households.
The purpose of the salt tank is to hold a supply of salt near the outlet of the water softener so that as the resin within the water softener cartridge becomes depleted, the salt will be available to re-salt the water upon demand. The salt will also act as a barrier to prevent any additional salt from entering the system during periods of low usage or when more dilute water is desired for some reason (such as when drinking water is sourced from different parts of the house).
Salt does not degrade over time and should therefore never be discarded. Instead, it should be kept in its original packaging in a dry, dark location for future use. Be sure to follow manufacturer instructions on how to dispose of salt waste. Some jurisdictions may impose restrictions on where it can be disposed of.
If there are no longer any packets of salt in the salt cellar/shaker then it means that the salt supply is running low. It is recommended that you replace the salt supply before replacing the resin cartridge.