Correct Water Conditions
Once detected, any problems with the condition of your Koi pond water will need to be corrected.   Most test kits will have instructions included on how to correct the problems with your water.  Here is a quick explanation of what you might find in your Koi pond water.

Ammonia.  Ammonia is present in fish waste, so it would seem logical that you have too many fish.  But, since you have not yet added fish it could be your water supply.  Some public water supplies contain ammonia if they have been treated with chloramines.  The ammonia chips shown at left are an ammonia-removing chemical filter media for clean and healthy water .  It continuously removes toxic ammonia produced from fish waste and improves water quality in freshwater ornamental ponds.  Ammonia chips remove deadly ammonia with the natural ammonia-removing mineral zeolite.  It is an easy to use chemical filter media that continuously removes ammonia in new or established acquatic systems. Chlorine.  This is the iconicon most common chemical found in municipal water supplies.  Chloramine.  This is another additive used to purify city water supplies.  A combination of chlorine and ammonia, it is more toxic to fish than chlorine and will not dissipate from the pond the way chlorine does.  Just to be on the safe side, before adding any Koi fish or plants to your pond, you should give your Koi pond a dose of a general-purpose water conditioner.
Water conditioners should not be used in your Koi pond unless tests show that they are actually needed.  Just as you should not use chemicals in the rest of your garden unless a good reason exists, the same is true for your Koi pond. Too many chemicals will create more problems in your water than they cure, and can be harmful and even toxic to your Koi fish and plants.
If you do use a water conditioner to correct initial problems such as a high ammonia level, chlorine, or chloramine for instance, try to determine the source of the actual pollution to prevent any future problems.  By following these prevention tips you can be assured of having a Koi pond with good water quality that will be safe for your Koi.