Just as the ecosystem in nature is very fragile and likely to trigger serious consequences if the balance of the elements is altered, the ecosystem inside an aquarium is also very fragile and can have devastating consequences if the balance is broken. This is why it is important to regularly test the elements of water and make necessary changes as often as possible.
Many elements are important for the well-being of your aquarium fish; temperature and pH have the most immediate impact on their well-being and should be closely monitored. Some precursors can be tested in order to anticipate problems related to these elements. By closely monitoring these precursors, a careful owner can prevent the death of his fish, in the same way, that a careful doctor can prevent the formation of cancer.
The carbonate hardness, or kh, level of the water should be closely monitored using one of the commercial systems available on the market. These systems can be purchased at any saltwater fishmonger or online retailer such as Amazon.com. Water hardness is important because it can cause rapid changes in pH. These variations can stress fish, making them more susceptible to disease than they otherwise would be.
This means that it takes very little to make them sick; the germs from the fingers of a human hand could be enough to cause an outbreak and wipe out your entire aquarium population. Remember what smallpox did to Indian people because their immune system was unprepared. The consequences could be just as fatal.
In general, fish adapt fairly quickly to local water hardness, but in order for them to really thrive, their environment needs to be as close to their natural habitat as possible (i.e. where they would live if they weren't living in an aquarium in your home).
This is especially necessary if you plan to breed your fish. Keep in mind that, just like human newborns, baby fish will not have had a chance to adapt to an environment that did not suit them, and many may die as a result. Organic aquatic plants also grow best in water that closely resembles their natural habitat. There are many commercial products that will soften the water if the kh level is too high.
By carefully monitoring the kh level of your aquarium, you will be one step ahead of the elements and help give your fish the best possible chance of survival.