On a Morton System Saver, there's a setting labelled hardness, but no clear indication as to what setting is "recommended" -- or even whether this setting is the desired "output" or "input" hardness (hardness to compensate for). The instructions simply instruct the user to "adjust the hardness setting" as necessary.
My UX intuition would suggest that this is the desired "output hardness." My CS intuition suggests that this is a compensation level. And neither intuition has a clue what "normal" would be.
Is there a "normal" value I can set to get water that leaves minimal deposits but still lets you rinse the soap off your hands easily? Or, do I need to get the water tested and set the hardness according to the test results?