Ask 'Dr. Spa' Q & A Message Board

The numbers aren't that bad, but try bringing the pH down to 7.2 to see if that brings the deposits into solution. Next fill, try getting the pH down to 7.2-7.4 before adding any calcium, then add the calcium slowly (little doses every day to allow it to get in solution), and stop on the low end of the range (150). If it turns out that the calcium is the problem, you can run with even lower hardness, just make sure to watch the pH. FYI, I believe the stain/scale product is supposed to prevent precipitation from occurring, but I don't think it can bring scale back into solution.

Doc has posted methods to determine whether the material is organic or mineral -- basically treating it with chlorine and acid to see which makes it dissolve. Perhaps the info is in one of the pulldown menus, or the FAQ. If it is indeed calcium, you can try driving the pH down even lower to get get the scale back in solution, then raise the pH back up to reduce risk of corrosion.