Reading a water test without panicking

A liquid test kit is a set of three numbers, not a diagnosis. Ammonia and nitrite should be zero in a running tank. If either is not zero, stop feeding, change water, and do not add fish.

Nitrate is the leftover. Keep it low with regular water changes. Higher means you are overfeeding or under-changing, not that the tank is about to crash today.

Read the bottle. Match the colour in daylight. Write the numbers down. The panic comes from guessing; the action comes from a number you can check tomorrow.

Written by the index editors. Corrections to hello@ilovethatfish.com.