About a year and a half ago, I had an Autotrol softener installed in my new house. The water softens very well, but there is always a white powdery residue left after the water dries. I tried different salt settings but cant seem to cure this problem. This house is brand new, has new well, new plumbing etc. Any ideas on what may be the cause? Oh, I also use Morton salt pellets. Thanks in advance.