RE: Product Questions (calcium supplement)...
In theory Kalk will convert carbon dioxide into bicarbonate thus increasing alkalinity. In reality, I think most of the heavy Kalk users will tell you that it doesn't create enough carbonate to keep alkalinity levels where they need to be and additional buffer needs to be added.
As with any supplement, testing is essential to tell you how good a job you are doing to keep your levels where they need to be.
Gary
125 SPS, 75 gal. LPS/softie reef, 9 gal. Nano