Our Coral Essentials, Part B Carbonate is a concentrated liquid solution of carbonate and bicarbonate salts, 200,000 ppm (mg/L) or 11,200dKH. Carbonate is also an essential component in the formation of calcium carbonate skeletons, i.e. coral growth. The alkalinity levels in marine tanks need to be checked regularly to determine the carbonate take up in your system. How much carbonate is being used can be calculated by testing at regular intervals to see how much the KH level drops during the set interval. Then it is simple to calculate dosing requirements to suit the depletion rate. After you have determined this, a regular check of the KH levels should be made. Your tank will change over time as coral grows, new pieces are added as well as invertebrates that also take up carbonate. We have found ideal KH levels to be at about 8-9 dKH for most aquariums. Levels of 8.5 – 9.0 dKH are desirable if you want to maintain high levels of growth in a SPS and hard coral dominant system.