The Nitrogen Cycle
Beneficial bacteria convert toxic ammonia to nitrite and then to nitrate. A mature aquarium should consistently test zero for ammonia and nitrite.
Nitrate
Nitrate accumulates more gradually and is controlled through stocking, feeding, plant uptake, filtration practices, and water changes.
pH
pH describes acidity or alkalinity. Stability is often more important than repeatedly adjusting a suitable pH to chase a textbook number.
GH & KH
General hardness reflects dissolved calcium and magnesium, while carbonate hardness helps buffer pH. Both can influence species suitability and stability.
Temperature
Temperature affects metabolism, oxygen demand, feeding, and disease dynamics. Use a reliable heater where required and verify temperature independently.
Test Trends
Record results and learn what is normal for your aquarium. A trend away from normal can be more informative than a single isolated reading.