**The switch changes the regeneration program—the cycle that recharges the resin with brine. A mismatch can reduce softening performance, especially if you’re using KCl with the controller set to NaCl.** The exact adjustments depend on your model.

**1) What does the setting change?**

For example, the Morton M45 manual explicitly says the setting “adjusts the regeneration cycle times” to compensate for KCl’s different dissolution rate. It doesn’t specify which stages change or by how many minutes. So without your make and model, claiming that the switch always adds a particular amount of salt or rinse time would be guessing. [Morton M45 manual, page 14](https://www.mortonwatersofteners.com/wp-content/uploads/2019/04/M45-7369502_C-Sm.pdf)

The controller needs to account for differences in brine preparation and regeneration performance. KCl can require more regenerant to achieve the same useful softening capacity. Some machines accommodate this through programming; others require manual adjustments. [University of Nebraska–Lincoln Extension](https://extensionpubs.unl.edu/publication/g1491/na/pdf/view)

**2) Could an incorrect setting explain hard water?**

| Salt actually used | Controller setting | Likely consequence |
|---|---|---|
| KCl | NaCl | Inadequate regeneration or less capacity than expected, potentially allowing hardness through before the next cycle. |
| NaCl | KCl | Generally unnecessary regeneration compensation, potentially wasting salt, water, or time; less likely to explain persistent hard water. |

Those are general expectations, rather than a diagnosis for your particular controller.

Check the bag, match the setting, and run a manual regeneration according to the manual. Then test **cold water from a tap supplied by the softener**, after flushing the pipe:

- **Soft afterward, then hard before the next regeneration:** points toward insufficient capacity or incorrect regeneration settings.
- **Hard immediately afterward:** investigate bypass position, brine delivery, and valve/resin problems. A blocked injector/venturi, for example, prevents brine reaching the resin. [Morton maintenance guidance](https://www.mortonwatersofteners.com/maintenance/common-maintenance/)

A declining salt level indicates consumption, but doesn’t establish that regeneration is effective. Your make and model would let us identify precisely what that toggle changes.