Sea water contains more than 60 elements. The main one is chloride, which accounts for more than 54% of the total mass of salts, followed by sodium, with around 30%. When these two elements bond, sodium chloride is formed. This is the main salt in sea water, comprising around 85% of the total; the other salts therefore represent only 15% in all, but they all play an equally important role. Magnesium, sulfur, calcium, potassium, and bromide are the most abundant elements,
Sea water contains a great deal of calcium carbonate and bicarbonate, and there are only slight variations in pH in a natural setting. It is a different matter in an aquarium, a restricted habitat operating as a closed cycle. The pH must not fall below 8, but a slow and regular decrease in this parameter may be seen. Why? The water in an aquarium sometimes contains too much carbon dioxide, which has a tendency to lower the pH.
What can you do? The first step is to measure the CH:
- if it is under 7.2°CH, add calcium or replace some of the water. This situation is, however, fairly rare in an aquarium without corals, solely occupied by fish;
- if it is over 7.2°CH, there is an excess of carbon dioxide. Stirring of the water must therefore be increased by using diffusers or an electric pump.
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