When a test is done, and the 'max' is reached, you usually need to interpret the result as being "X or higher", and not "X"! In your case, the first test did NOT mean your CYA=100; it mean your CYA = 100 . . . OR any higher value, including 500! Most likely, the 2nd result is also a 'max', indicating your CYA is 250 or MORE.
Once you get the K2006 (http://pool9.net/tk/), you can do an accurate dilution with distilled water, and test up to 500 ppm CYA.
Bookmarks