"www.GymRatZ.co.uk" wrote:

The water in the salt compartment (saline) is merely for regenerating
the resin beads and gets flushed to waste. Isolated from Domestic water
by valve trickery.

The encrusted salt in the container is fine doesn't cause any problems
either in-situ or falling off into the water at the bottom.

Ah, splendid, thanks. I might gently break off the bits clinging to the
walls and see if it returns, though I suspect its appearance might somehow
be connected to the fact that I recently inadvertently let the salt run
completely out: I'd certainly never noticed it happening previously.