In the city water supply system, the water hardness is quite high, so often the aquarist needs to lower it. The inhabitants of the aquarium do well in water with a hardness level of 3 to 15 degrees. Some snail species cannot live in soft water as their shells begin to break down. Viviparous fish should be kept in water with a hardness of about 10 degrees. For neon fish, the water hardness should not exceed 6 degrees. Sagittaria and water fern germinate well in water with a hardness of 10-14 degrees, and uviranda dies even at 5 degrees.
Remember that the water hardness level changes with the season. Many people know that boiling reduces this level well, but this applies only to the temporary component of hardness. In stable times of the year - towards the end of summer and towards the end of winter - it increases, and rains and floods lead to softening of the water. Therefore, in the springtime, fish are prepared for spawning and plants begin to grow.
Plants such as elodea, hara algae, hornwort perfectly soften water. Their leaves and stems are usually covered with a crust, which is a precipitate of calcium salts. Plants do not absorb carbon dioxide at night, and in the process of breathing of living creatures in the reservoir, it accumulates in the aquarium, as a result of which the water hardness increases. If there are sharp fluctuations in the level of rigidity at night and during the day due to the presence of a large number of these plants, it can kill all animals in just one night: they will simply suffocate. That is why water bloom is a very unpleasant and dangerous phenomenon in an aquarium. Remember, this can start in brightly lit tanks with rotting food debris. The addition of distilled water will help reduce the permanent hardness of the water.
In addition to ordinary boiling, there is another method of obtaining water with hardness, the level of which is close to zero. To do this, you need to fix a glass plate in front of the spout of the boiling kettle. Place a container on its lower edge to collect condensed vapors. The water obtained in the container in this way will have a hardness close to zero.
The hardness of the water can be reduced by simple freezing. Pour 3/4 of the water into an empty plastic bottle, close and place in the freezer. When about half of the water freezes, remove the container from the refrigerator. After that, carefully cut the bottle and remove the frozen part of the water. This piece of ice, when melted, becomes water with a very low level of hardness.