General Hardness (GH) in an aquarium refers to the concentration of dissolved magnesium and calcium ions. Elevated GH levels can negatively impact aquatic life, particularly sensitive fish and plant species. For example, certain soft-water fish, like tetras and discus, may experience stress, reduced breeding success, and shortened lifespans in water with high GH. Similarly, some aquatic plants struggle to absorb nutrients effectively in hard water conditions, leading to stunted growth and poor health.
Maintaining appropriate GH is crucial for a thriving aquarium ecosystem. Water parameters mimicking the natural habitat of the inhabitants contribute significantly to their overall health, vitality, and longevity. Historically, understanding and managing water hardness has been a cornerstone of successful aquariums, dating back to the early days of the hobby where observation and adaptation were key to keeping exotic species alive.