Carbonate hardness is an indicator of the level of bicarbonate. In saltwater is an important buffer. Bicarbonate will be dissociated and become HCO₃^-, CO₃^-, CO₂, H⁺, OH^-,etc. to stabilize the buffer system and maintain the ph value. Besides,KH will influence CO₂ solubility and it is also the source of biogenic decalcification for saltwater plants.