Salifert KH/Alkalinity Test Kit. Calcium alone cannot form the skeletal material of corals and allow calcareous algae to grow. Some other substances are needed as well. A few other constituents are carbonate and bicarbonate. These two substances also have a major impact on the stabilization of the pH in the proper range of 8.1 – 8.4. Such stabilization is also called buffering. The total carbonate and bicarbonate concentration is also called carbonate alkalinity or carbonate hardness. The only difference between alkalinity and carbonate hardness is a conversion factor. NSW has an alkalinity of approx. 2.7 meq/L or approx. 7.5 dKH when expressed as carbonate hardness. For a stable system the alkalinity or carbonate hardness should have a value similar to NSW or slightly higher and should preferably not fluctuate by more than 5%. This means a maximum fluctuation of 0.14 meq/L or 0.4 dKH. Therefore an alkalinity test kit should be capable in measuring in steps smaller than 0.14 meq/L. The Salifert KH/Alk test is very straightforward. It measures in sufficient small steps of 0.1 meq/L or 0.3 dKH with a sharp color change. This makes detection of important yet small change possible. The kit can perform approx. 100 - 200 measurements.