Gesamthärte

Gesamthärte, often abbreviated as GH, is a measure of the concentration of dissolved calcium and magnesium ions in water. These ions are commonly referred to as "hardness-forming" substances. Gesamthärte is typically expressed in degrees of German hardness (°dH), although other units like ppm (parts per million) or millimoles per liter may also be used. The higher the Gesamthärte value, the harder the water.

The presence of calcium and magnesium ions influences various aspects of water quality. In aquatic environments, such as aquariums, Gesamthärte plays a crucial role in the health and well-being of fish, invertebrates, and aquatic plants. Many species have specific Gesamthärte requirements for optimal survival and breeding. For instance, some fish species thrive in soft water, while others prefer hard water.

In households, Gesamthärte impacts the effectiveness of soaps and detergents, as hard water can reduce their lathering ability and lead to the formation of limescale deposits in pipes, appliances, and on fixtures. Limescale is primarily composed of calcium carbonate, which precipitates out of water when heated or when the water evaporates. Understanding and managing Gesamthärte is important for both domestic use and in specialized applications like brewing and water treatment.