MARINE KH PLUS is a liquid solution for increasing carbonate hardness (KH) in the marine reef aquarium. Seawater has a carbonate content between 8 to 9 degrees German (°d).

In the aquarium, it is recommended to keep this value between 8 and 10 degrees to avoid sudden changes in pH.

KH is a measure of the alkalinity of water produced by the presence of CO32- and HCO3- carbonates. Its princiaple component is largely provided by carbonates, calcium bicarbonates and magnesium bicarbonates, and is measured based on the amount of acid required to produce a pH shift that converts all bicarbonates (HCO3-) to carbonic acid (H2CO3).

A correct alkalinity value of water allows the pH to be kept stable. The buffering action of KH is represented by this reaction:

CO² + H²O ↔ H²CO³ ↔ H+ + HCO³-

CO² = carbon dioxide
H²O = water
H²CO³ = carbonic acid
HCO³- = bicarbonate ions
The effect of adding CO² to seawater creates an increase in the contraction of H²CO³, HCO³- and H+ and a decrease in the concentration of CO³²- which lowers the pH.

CO² + H²O ↔ H²CO³ ↔ H+ + HCO³- ↔ CO³³- + H+

CO³²- = carbonate (precipitates).
Just as with calcium and magnesium, KH is critical for healthy coral growth.

 Skeletal growth is affected by KH as it is involved in the transition from bicarbonates to carbonates, so this dissolving power of KH, serves to balance the amounts of calcium and magnesium that can be dissolved in water. If we want to raise the calcium level to facilitate coral growth, we must inevitably raise the KH; this way calcium and carbonate ions meet in solution and stabilize each other, without creating precipitation.

Available sizes:

250 ml - Product code RKH