What is KH and GH in Aquarium Water Test Kits?

In aquariums and fish farms, you need to be able to differentiate between Carbonate Hardness (KH) and Total Hardness (GH).

Carbonate Hardness

Carbonate hardness (KH or CH) refers to the ability of the water to maintain a stable environment and subsequently, the health of fish. The carbonate hardness is the ‘buffering’ ability of the water. To determine this on a photometer you need Palintest Alkalinity tablets, known as Alkaphot (part code AP188).

Total Hardness

General hardness (GH) refers to the ‘hardness’ of the water caused by calcium and magnesium ions. Different aquatic species prefer different environments, some prefer ‘hard’ water and some prefer ‘soft’ water. The hardness of your water is often dictated by the source of the water. If it’s from groundwater it tends to be harder, if it’s from surface water it tends to be softer. To determine this on a photometer you’ll need our Hardicol reagent (part code AP254).

Sometimes the units dH are used. This means “degrees hardness”. Most test kits define results in terms of ppm CaCO3 means ‘parts per million equivalent to that of calcium carbonate’ – it doesn’t mean that the hardness is in this form.

1 unit dH equals 17.8 ppm as CaCO3.

Aquarium Water Testing

Our range of photometers are the ideal solution for monitoring your Aquarium, with single and multiparameter platforms, you can select the solution right for you. Click here to view our range of photometers. 

To view information about reagents and to search for ordering information, please click here

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