Twelve guides on the water a koi pond runs on: KH and carbonate hardness, pH crash, dissolved oxygen, ammonia and nitrite, temperature, salt, water changes, green water and algae, filter cycling, and what continuous measurement shows that spot testing does not. Each sets out what the parameter does, what moves it, and where the limits sit. The scope is water chemistry — not disease, parasites or fish health in general.
KH (carbonate hardness, or alkalinity) is what holds koi pond pH steady. Target 105-180 ppm CaCO3, or 6-10 dKH, and how to raise it without a pH crash.
A pH crash is what happens when a koi pond's carbonate buffer runs out: pH collapses overnight. What causes it, the warning signs, and how to respond.
Why koi die suddenly with no visible disease: overnight oxygen crashes, pH crashes from low KH, ammonia and nitrite spikes, and what to do in the first hour.
Dissolved oxygen in a koi pond: why levels bottom out before dawn, what 7-10 mg/L means for your fish, and how to aerate and measure it year-round.
Ammonia and nitrite in a koi pond: why the same ammonia reading is far more toxic at high pH and warm water, what causes a spike, and how to respond calmly.
New pond syndrome is how most beginners lose koi: an ammonia spike, then nitrite. How to cycle a pond filter safely, and what wrecks a mature one.
Koi pond water parameters in one reference table: targets for pH, KH, ammonia, nitrite, nitrate and dissolved oxygen, plus how fast each one can change.
Measuring pond water electronically: drop tests, strips, pH pens, DO meters, photometers and continuous sondes compared honestly, including probe drift.
Koi pond water changes: how much, how often, and how to do them without shocking fish. Why 10-20% weekly beats rare large changes, plus KH and dechlorination.
Koi pond water temperature drives feeding, immunity and oxygen. A season-by-season guide to the koi year, the spring danger window, and winter care.
Salt in a koi pond is a real tool and a common mistake. What it does, safe levels in ppm, why it never leaves on its own, and how to measure it.
Green pond water and string algae are two different problems. Why a heavy algae bloom swings pH and oxygen daily, and how to restore clarity safely.
