Reducing the mineral content, specifically calcium and magnesium, within a closed aquatic ecosystem is a process that aims to lower the general hardness (GH) and carbonate hardness (KH) of the water. Elevated levels of these minerals can be detrimental to certain species of fish and invertebrates. For example, a freshwater environment intended for South American tetras requires significantly lower mineral concentrations than that tolerated by African Rift Lake cichlids.
Maintaining appropriate water parameters is crucial for the health and well-being of aquatic inhabitants. Many ornamental fish and plants have evolved to thrive within specific ranges of GH and KH. Replicating these natural conditions in a captive environment can improve breeding success, reduce stress, and enhance overall vitality. Historically, hobbyists have employed various techniques, from rainwater collection to specialized filtration media, to manipulate water chemistry and provide optimal conditions for their aquariums.