Hard water

Term qualifying water loaded with dissolved salts, especially calcium and magnesium.

Hard water is water that contains a high concentration of dissolved minerals, including calcium and magnesium. We often speak of hard water when its hardness is more than 17.8 ° DH (German degrees of hardness).

The hardness of the water is measured in MG/L (milligrams per liter) of carbonate calcium (CACO3). We speak of fresh water when the hardness is less than 17.8 ° DH and very hard water when it exceeds 50 ° DH.

Hard water tends to be richer in minerals and is often considered healthier to drink than fresh water. However, in the field of aquarophilia, hard water can cause problems for fish and aquatic plants.

Calcium and magnesium contained in hard water can be beneficial for aquatic plants because they are necessary for their growth. However, too high a concentration of these minerals can harm certain species of fish and plants.

For example, some fish, such as discus and angels, need fresh water to reproduce and develop properly. Likewise, some plants, such as anubias and cryptocorynes, prefer fresh water and may have trouble developing in too hard water.

It is therefore important to know the hardness of the water from your aquarium and choose the species of fish and plants accordingly. If you use hard water in your aquarium, you can use chemicals to make it softer, but it is best to be careful and not add too much so as not to disturb the balance of the aquarium .

It is also possible to use osmosis water or rainwater to dilute hard water and give it a hardness more suitable for your fish and plants. It is important to find out about the water needs of each species and regularly measure the hardness of the water in your aquarium to ensure that all the creatures that live there are healthy.