Koi and Pond Care
Pond Water Quality and What You Should Really Know
In general, everything you should know about your pond water is available in some sort of simple test kit. Most kits are very easy to run. You can buy these kits at your local shop. Run them at least weekly during the first part of opening your koi pond, then monthly (or more) during the season. If your koi ever get sick or start acting funny, you should know that SEVENTY PERCENT of koi health problems (including vulnerability to disease‑causing organisms) are related to POND WATER QUALITY. Do not make the mistake of blowing off the importance of testing your pond water for pH and ammonia in particular at the first sign of trouble.
Ammonia
Nitrite
Nitrate
Hydrogen Sulfide
pH
pH Crash
Oxygen
Carbon Dioxide
Water Changes
Algae Control
You might also value this discussion of Bacterial infections.