Carbonate hardness, also known as KH, measure the amount of carbonate and bicarbonate ions already present in an aquarium water. Carbonate hardness is important in aquarium water because the carbonate hardness act as a buffer to neutralize any acid that are present in the water. The acids in the water come from the waste produce by the fish, decaying plants, and carbon dioxide that may be inject into the water.
If the carbonate hardness of the water is too low, the acids in the water will lower the pH of the water rapid. Low level of pH are harmful to the fish in the aquarium. Carbonate hardness is therefore important in provide stability to the pH of the water in the aquarium.
Carbonate hardness in aquarium water and why it matters
Carbonate hardness is measured alongside the general hardness of the water and the pH of the water. General hardness test for the amount of calcium and magnesium present in the water. The pH test measure the level of acidity of the water.
These three test are connected to each other. For instance, if you add carbon dioxide gas to the water to lower the pH of the water, high carbonate hardness will make it more difficultly to lower the pH of the water. To lower the pH of the water with high carbonate hardness, more carbon dioxide must be added.
However, adding too much carbon dioxide to the water can lead to depletion of the dissolved oxygen levels in the water, which is also necessary for the survive of the fish. Depending on the type of fish to be kept in the aquarium, the level of carbonate hardness required in the water can differ. For example, fish from the Amazon region require water with low level of carbonate hardness.
These fish prefer water with high amount of tannins. In contrast, fish like the African Rift Lake Cichlids require water with high levels of carbonate hardness; there native homes have high levels of alkalinity in the water. Similarly, fish like guppies and mollies prefers higher levels of carbonate hardness in the water.
Depending on the species of fish to be kept, the aquarist should adjust the level of carbonate hardness to that of the requirement of the fish. If the level of carbonate hardness in the tank is too low, there are steps that can be taken to increase the carbonate hardness of the water. One way to increase carbonate hardness quickly in an emergency is to use baking soda.
However, you should premix baking soda with water and add to the tank in measured amount so that the water parameter are not altered drastic. Other long-term method of increasing carbonate hardness is to add crushed coral or limestone rocks to the tank. These rocks will dissolve slowly in the water to gradual increase the carbonate hardness of the water in the aquarium.
Conversely, if the carbonate hardness of the water in the tank is too high, steps can be taken to decrease the carbonate hardness of the water in the aquarium. One way to decrease carbonate hardness is to use RO (reverse osmosis) water. RO water does not contain many minerals; using this water will lower the carbonate hardness of the tank water over time.
Another way to lower carbonate hardness is to use peat or almond leaf in the aquarium. When adjusting the carbonate hardness in the aquarium water, it is important that the changes made are slow. Rapid change to the carbonate hardness of the water can result in osmotic shock in the fish.
If the fish experience osmotic shock, it can be fatal to the fish. Therefore, changes in carbonate hardness should be made slow so that the fish can adjust to the changes in the water. The carbonate hardness of the aquarium water should be test regularly.
There are a few different way to test the carbonate hardness of the water. Using a liquid test kit will ensure reliable result; liquid test kits work by changing color in response to the carbonate hardness in the tank water. Test strip can also be used to test the carbonate hardness of the water.
However, test strips are not as precise than the liquid test kits. Digital meter can also be used to test the carbonate hardness. Digital meters provide the most accurate measurement of carbonate hardness.
Testing the carbonate hardness of the water should of been performed before each water change and in the morning prior to start the CO2 cycles for the planted aquarium. There are some common mistake made by those who manage the carbonate hardness of the water in aquariums. One of the most common mistake is to confuse carbonate hardness with general hardness.
Using the wrong type of mineral to adjust the general hardness of the water will affect the health of the aquariums fish. Another mistake is to not maintain enough attention to the carbonate hardness to ensure that it does not drop to too low of a level. Finally, ensuring that any change to the carbonate hardness are made slowely to avoid shocking the fish and making their system work against the processes it perform naturaly for the survive of the fish in the tank.
