Chemical Parameters.

These include pH, KH, GH and oxygen and are grouped as chemical parameters as their levels are caused by chemical interactions (some of which may be directly related to other biological processes).

pH. pH measures the acidity or alkalinity of pond water. A koi pond's pH should fall between 7.0 and 9.0, ideally being stable around 8 and 8.5. This slightly alkaline pH (7 being neutral) suits the environmental requirements of koi and with a little effort, should be relatively easy and inexpensive to maintain.

KH. KH is a measure of the soluble carbonate/bicarbonate ions that act as a buffer to maintain a stable pH. A medium to high KH shows that the pH is not likely to fluctuate and is therefore the most desirable.

GH. GH measures the general hardness of pond water, particularly the hardness forming ions of calcium and magnesium. The GH should be medium to high in order to match the conditions that is preferred by the koi physiology.

Oxygen. Oxygen, like all of the preceding parameters is required at a minimum level. It dissolves in water and can be easily added using diffused aeration, venturis, moving water or through plant photosynthesis (although this is less common in a koi pond, unless it is suffering from blanketweed). Water will hold less oxygen in warmer water (just when koi and bacteria require more) and if a pond is excessively planted, may well suffer from dawn depletion as DO levels drop at night through excessive plant respiration.

Why Test? Whenever the quality of a substance is at issue, it must be compared to a 'standard' or 'benchmark' in order to put it into context. Water quality is no different and when we test a sample, besides analysing it and gathering basic data, we can also compare it against what is desirable. Furthermore, as soon as we are able to measure something, we are in a position to measure it and thus we can manage and ensure that it reaches at least the minimum standard.

If by testing, we can verify that our pond water is satisfactory, then we can gain a degree of confidence that the health of our koi should be satisfactory, at least in the medium term. Furthermore, testing and logging data should allow us to detect any deviations from the norm before it starts to have a significant negative effect on koi health. What better confidence booster could there be than to verify through testing, that your koi are being provided with only the best water quality.

Regular testing will also highlight variations or instability in any of the parameters, allowing you to intervene and improve the quality of the koi's environment.