I ran across this US Patent for removing CYA from Pool Water. (This is not related to the Bioactive threads)
Here's a link
And here's a Wiki article that has some information about melamine reacting with CYA to form an insoluble precipitate.
From what I understand the CYA test uses melamine which clouds the water with the precipitate, when is then used to perform the turbidity test.
Since this patent doesn't seem to have found commercial application, I'm wondering why. Safety? Economics? Not practical for some other reason?