Water Chemistry
The parameters that matter most are ammonia, nitrite, nitrate, pH, KH (carbonate hardness), and dissolved oxygen. These interact in ways that can be counterintuitive — for example, the toxicity of a given ammonia reading depends entirely on pH and temperature. The guides in this section explain each parameter, how they relate, and what to do when levels fall outside safe ranges.
Guides in This Section
The Nitrogen Cycle
The biological process that converts toxic ammonia to nitrite to nitrate — the foundation of every healthy koi pond.
Ammonia & Nitrite
Understanding NH₃ vs NH₄⁺, pH-temperature interaction, nitrite and brown blood disease, and emergency response protocols.
pH, KH & GH
How pH affects toxicity thresholds, KH as the buffering backbone, GH and mineral balance, and safe adjustment methods.
Dissolved Oxygen
Why oxygen is the most critical and most overlooked parameter — temperature effects, saturation tables, and aeration sizing.
Phosphorus & Algae
The phosphorus–algae connection, testing methods, source reduction, and chemical vs biological phosphate removal.
Water Testing Guide
Which parameters to test, how often, liquid vs strip accuracy, and how to interpret results in context.
Water Changes
Volume, frequency, temperature matching, and how water changes interact with biological filtration and pH stability.
Dechlorination
Chlorine vs chloramine, treatment methods, dosing for water changes, and what happens if you skip this step.
Related Tools
- Ammonia Toxicity Calculator — calculate free ammonia (NH₃) from your total ammonia, pH, and temperature
- Salt Dosage Calculator — calculate salt doses for treatment and nitrite detox