An aquarium contains just a tiny amount of water volume compared to natural waters. This has the disadvantage that all the water values can fluctuate from one extreme to the other in a very short time. However, a high level of stability and consistency is required for successful aquarium maintenance. The important thing here is a chemical analysis system that can be used to diagnose the water and can form a basis on which the cure (e.g. using water maintenance and filtration products) can be deduced.
Water testing kits from the Dupla brand are generally acknowledged as being among the most accurate tools in the aquaristics industry. Only through regular checking and reliable results can an aquarium be prevented from being 'unbalanced'. The most important water values that need monitoring in a freshwater aquarium are the pH value, the nitrite content and the carbonate hardness. For tanks with plants, it is also very important to check the iron content.
Marine water aquaria in particular will not achieve the most important water values without regular checking. The concentrations of the key elements of calcium and magnesium especially are constantly changing in the aquarium, because they are consumed by corals and algae or are reduced by precipitation. Many organisms react very sensitively to such fluctuations in the water values.