kH, or carbonate hardness, measures the concentration of bicarbonates and carbonates dissolved within aquarium water. These minerals act as a natural buffer against sudden pH swings, making kH one of the key factors controlling water chemistry stability.
Different fish species originate from very different environments and therefore require different carbonate hardness levels to thrive. Soft water species such as Cardinal Tetras, Discus, Angelfish and Apistogramma naturally inhabit waters with very low mineral content, while livebearers and African cichlids require harder, more mineral-rich conditions.
Fish Science kH Reducer allows aquarists to safely and gradually lower carbonate hardness without shocking aquarium inhabitants or destabilising the aquarium system. Lowering kH can also make pH easier to manage and stabilise, particularly in planted aquariums and soft water biotope systems.
Maintaining appropriate kH levels helps support fish health, natural behaviour, breeding success and plant growth while reducing stress caused by unsuitable water conditions. The gradual action of Fish Science kH Reducer allows safe adjustment over time, helping avoid sudden parameter swings that can negatively affect fish and invertebrates.
Proper aeration during treatment is important, particularly when CO2 systems are present, as carbonate hardness directly interacts with pH and dissolved carbon dioxide levels.
Gradually lowers carbonate hardness (kH)
Helps stabilise and control pH
Supports soft water tropical fish species
Ideal for biotope and planted aquariums
Helps recreate natural water chemistry
Suitable for fish and crustaceans when used correctly
Supports long-term aquarium stability
Add 25ml per 100 litres to lower kH by approximately 2°. Do not reduce kH by more than 1° per day.
