If a body of water is out of balance, this can often be seen by external changes to the water. However, the basic water values pH and KH (carbonate hardness) should be checked regularly before it reaches that point. These self-administered rapid tests can be used to check whether the water is healthy and stable. The pH value should then be between 7.5 and 8.5 and the KH value between 5 and 14°dH. If a body of water is already showing symptoms of imbalance, looking at different values can provide information about the causes.