Ichthyological terms, not general ones.
Measure of the alkalinity of water as dictated by the presence of bicarbonate and carbonate ions. Usually expressed as parts per million, milligrams per litre, or degrees (dKH) of which 1 dKH corresponds to 17.848 ppm. Sometimes used a synonym for, but not equivalent to, temporary hardness.
Used in 65 profiles
Refers to the portion of hardness in a water body arising from the presence of dissolved calcium hydrogencarbonate and magnesium hydrogencarbonate. These become less soluble as temperature increases so are removed when water is boiled, for example. Temporary hardness is sometimes referred to as, but is not equivalent to, carbonate hardness.
Used in 1 profile
Commonest unit of measurement for carbonate hardness used in aquaria, and an abbreviation of the German term 'Karbonathärte'. 1 degree KH corresponds to a litre of water containing approximately 17.848 milligrams of calcium carbonate in solution.
Used in 4 profiles
Measure of the buffering capacity of a given water body, i.e. its capacity to neutralize acids and bases thereby maintaining a fairly stable pH. Water containing compounds, such as bicarbonates, carbonates, and hydroxides has a stronger such capacity and is referred to as hard water, while water lacking or deficient in them is termed soft water. Soft water aquaria tend to be susceptible to pH crashes if not maintained correctly.
Used in 6 profiles
Naturally-occurring, crsytalline form of calcium carbonate with a notable buffering capacity. Popular as a substrate or substrate additive in marine and freshwater aquaria where pH and hardness must be maintained at high levels, and has a more rapid, effective effect than coral sand, for example.
External skeleton, often forming a hard, shell-like outer covering typical in insects, crustaceans and some molluscs. Usually chitinous but may also be composed primarily of calcium carbonate or silica.