Water Expert Andy Ball: Problem with Salt

The salt not going down could be due to many different reasons.
1. Valve is not regenerating due to a mechanical problem. 2. Salt may be bridged (become solid) above water that is at the bottom of the salt tank. 3. If you have been using pellet salt for many years you could have a lot of undissolved residue at the bottom. This residue will not dissolve and also can block water flow in and out of the salt tank. 4. The valve could be failing to draw the brine solution out and if you have a float shut off in the brine tank, it would be prevent the salt tank from overflowing (which it would do if the float shut off was not there). 5. The brine refill control could be clogged, prevent water to refill the salt tank.
(Note: It is highly recommended that you contact an experienced water quality specialist to trouble shoot any problem with your equipment.)