Aquarium Water Parameters Explained
What ammonia, nitrite, nitrate, pH and hardness mean.
More AquaStocker tools & guides: Stocking & Compatibility Calculator · Fish Compatibility Checker · Fish Care Database · Build Your Own Aquarium · Aquascape Gallery · All guides
The toxic trio
Ammonia and nitrite should always read zero in a cycled tank — any amount is toxic. Nitrate is the safer end product; keep it under ~40 ppm with water changes.
pH and hardness
pH is how acidic or alkaline the water is; hardness (GH/KH) is its mineral content. Most community fish adapt to a stable value — stability matters more than chasing a perfect number.
Test, don't guess
A liquid test kit is far more accurate than strips. Test weekly while learning your tank, and any time fish look off.
Recommended gear
As an Amazon Associate we earn from qualifying purchases.
FAQ
What should aquarium water parameters be?
Ammonia 0, nitrite 0, nitrate under ~40 ppm, and a stable pH your fish tolerate. Stability beats a 'perfect' number.