Ammonia, nitrite and nitrate

The nitrogen cycle turns waste into different readings. Knowing the difference helps you respond calmly.

For axolotl care, the short version is simple: ammonia and nitrite should be zero in a stocked tank. Nitrate should be controlled.

Ammonia

Ammonia comes from waste, uneaten food and decaying material.

Any detectable ammonia in a stocked axolotl tank is a warning sign. Check the test, remove waste, review feeding, consider a water change and get experienced help if the animal has been exposed.

Nitrite

Nitrite appears after ammonia is processed by part of the biofilter.

Nitrite should also read 0 ppm in a stocked axolotl tank. Detectable nitrite can mean the cycle is incomplete, overloaded or disrupted.

Nitrate

Nitrate is usually the end reading of the cycle.

It is less immediately dangerous than ammonia or nitrite, but it is still waste. Manage it with water changes, sensible feeding, waste removal and enough tank volume.

What changed?

When a reading is wrong, look for a cause:

• New or uncycled tank
• Overfeeding
• Uneaten food
• Dead plant matter
• Filter media replaced or over-cleaned
• Too little water volume
• Missed water changes
• Temperature rising

Fix the cause, not only the number.