NT Labs MARINE KH Test Kit

KH, or carbonate hardness, describes the pH buffering capability of water. Water with the correct KH will resist changes to the pH, ensuring a stable environment for your aquarium’s inhabitants.  KH measures the concentration of carbonates and bicarbonates dissolved in the water which provide the pH-stabilising effect. In a reef aquarium, these are also an essential component for reef-building corals and other invertebrates with calcium-based exoskeletons.

As marine water ages, acidic processes in the aquarium consume the KH causing it to decrease. Furthermore, many marine invertebrates assimilate carbonates removing them from the water column. If the KH becomes too low, the pH of the water is at risk of significant fluctuations. It is these changes that cause stress to fish and make them more susceptible to disease. The KH should be tested frequently to ensure that it remains at the correct level to provide a stable environment for your aquarium’s inhabitants.

In natural seawater, the dissolved carbonate hardness is normally 7 dKH (or °KH), but you may wish to maintain a level between 7 and 14 dKH depending on your method of running the aquarium.