The carbonate hardness value (KH) represents the alkalinity – in other words the water hardness (in °DH).
The alkalinity depends on the amount of the ions in water with basic characteristics, mainly the carbonate content. Carbonates are important for the corals’ carbon supply. The carbon contained in the bicarbonates is important for the photosynthesis of the corals.
The higher the pH, the less CO2 is available to the corals. The correct alkalinity is very important for buffering, i.e. stabilisation of the pH value in the salt water aquarium. The regular measurement of KH content is therefore extremely important for a sea water aquarium, since a correctly adjusted KH value is necessary to stabilise the pH value as mentioned above.