Hard water in the aquarium
The hardness of water is the amount of minerals dissolved in it. If the amount of dissolved minerals is high-the water is hard, if low-then soft.
Water hardness increases when filtered through porous rocks such as chalk or limestone. Signs of high rigidity is the formation of lime plaque on pipes, taps and inside kettles, as well as the formation of foam on the water when adding soap. Hard water is found in areas such as lake Malawi, where fish are adapted to high hardness and pH levels.
Limescale and soap suds do not form in soft water. Soft water flows over hard rocks, such as granite, or through fallen leaves and peat, from which minerals are almost not washed away. A good example of a soft-water environment would be streams in the jungle, which are home to fish such as Tetra and corydoras that have adapted to acidic and soft water. Leaves and peat add tannic acids to the water, due to which the water becomes brown. This phenomenon is known as “Black water”.
There are 2 types of hardness-carbonate, or temporary hardness (it is also called alkalinity) and General, or permanent hardness.
Carbonate hardness accounts mainly for calcium carbonate (CaCO3) entering the water from chalk and limestone. This stiffness can be removed by boiling. A large amount of CaCO3 in water provides its high buffer properties, so the pH level of such water is much more stable than that of water with low carbonate hardness.
The stiffness constant takes into account all the minerals dissolved in the water. Boiling water does not reduce it. Stiffness can be measured in several ways:
Carbonate hardness is measured in mg CaCO3 per liter, or parts per million.
Constant hardness is measured by the amount of all dissolved minerals. When caring for fish, this stiffness is usually taken into account. It is also measured in mg CaCO3 per liter, or parts per million, (although other minerals are present in water), or-degrees of hardness. 1 degree is equal to 17.9 mg CaCO3 per liter.
To control the hardness of the water in the aquarium is very important, because if the water is too hard or, conversely, soft, it can serve to reduce the immunity of fish, making them more susceptible to infections.