I just visited two new prospects today.
Pool 1: CYA 90, Ca.... ta-da: ~800ppm (40Kgal). White stuff is shooting out of the plumbing (but other than a little MA, the pool looks good).
Pool 2: CYA... ta-da: I put in three-four DROPS and the black dot disappeared. I'm guessing around 1000ppm. And the pool's the prettiest shade of lime (as opposed to forest) green.
Just shakin my head here.