Freshwater Aquariums usually contain a variety of different organisms and animals, each with their own tolerance to different water parameters. The natural environments of these inhabitants are typically void of common tap water contaminants such as heavy metals, chlorine and chloramine. Many of the aquatic animals are thus extremely sensitive to these contaminants, so pure water is required in the aquarium.
A reverse osmosis system is the best option to ensure the best quality of water in the aquarium. Depending on the origin of the livestock, the water will sometimes need to be remineralised prior to adding it to the aquarium to ensure the desired levels of carbonate hardness (KH) and general hardness (GH) levels.