Koi pond water values check: what your test results mean
Enter your measured values and see at a glance what needs action today, what to keep an eye on and what is fine. Toxic ammonia is calculated automatically from ammonium, pH and temperature. Free, no account, nothing is stored.
Reference values for koi ponds
These four values matter most
KH, pH, ammonium and nitrite decide whether your koi are safe. With a KH below 3 °dH the water loses its buffer and the pH can crash overnight. Ammonium turns into toxic ammonia at high pH and warm water, nitrite blocks oxygen uptake in the blood.
Nitrate, phosphate and oxygen come second: they drive algae growth and become critical in summer heat.
Measure regularly and reliably
Test weekly during the season, always at the same time of day, and more often in spring, during heat, after filter cleaning or new fish. Drop tests are more accurate than strips. Test kits age – opened reagents last about 6–12 months.