API kH Test Kit
API KH Test Kit measures tap water fresh or saltwater aquariums for carbonate hardness (KH) and can be used to determine the proper dose of pH buffers.
KH is important for all types of aquariums and ponds. While different from pH, the two are closely related. We often begin to test KH after realizing there is a pH problem. In its most basic sense, KH is the measure of the buffering capacity of the water – the water’s ability to resist changes in pH. This is usually expressed as parts per million (ppm) of carbonate salts, hence the name “Carbonate Hardness.” Usually, high KH readings accompany high pH results. An extremely acidic pH usually results from a low KH.
Without an appropriate KH, the pH is likely to be wrong or unstable. In other words, it will be difficult to maintain the right pH without controlling KH. We can expect a gradual KH decline in most aquariums between water changes as the inhabitants and their wastes “consume” carbonates from the water. This is great another reason to keep up the regular care - partial water changes - as this helps replace lost buffering capacity.
Perform water changes with De-ionized (DI), Reverse Osmosis (RO) or Distilled water. These water sources should have KH of zero, so using this water to dilute the water in your aquarium will lower KH.
The first step is performing a partial water change. That may be all that is needed to raise KH. If you notice that your KH levels have not increased, use API Proper pH.