Quick take
Test hardness before and after the unit. That separates a real treatment failure from old scale still dissolving off fixtures.
Check bypass and plumbing
A partially open bypass or unsoftened branch line can send hard water to fixtures even when the softener itself is operating.
Verify the hardness setting
Metered systems need the source-water hardness programmed correctly. An underestimated hardness value can cause the resin to exhaust before regeneration.
Salt-free is not true softening
Salt-free conditioners are designed to alter scale behavior but do not remove calcium and magnesium. Spotting and measurable hardness can remain.
Use a simple hardness test
A before/after hardness measurement is one of the fastest ways to verify whether the ion-exchange process is actually working.