Calcium hardness test. What does it measure?

[cruzmisl]

Hi All,
Just curious what the calcium hardness test actually measures and what units it measures in, maybe ppm? I couldn't figure it out based on the instructions.
Thanks,
Joe

PS no jokes that it measures "calcium hardness" :-D

 

[mas985]

I believe it is ppm of Calcium Carbonate. See here.