Water Testing » Nitrate & Nitrite

Nitrate
Although nitrates are not as toxic as ammonia or nitrites, they must be monitored to avoid stressing the fish. Nitrates can also be a source of algae problems. Nitrates will rise over time and can only be eliminated via water changes. Monthly tests are important - particularly when breeding fish, as young fish are more sensitive to nitrates than adult fish. Test monthly and keep levels low to ensure a healthy tank.

Nitrite
During the startup of a new tank, nitrite levels will soar and can stress or kill fish. However, even after an aquarium is initially "cycled", it is not unusual to go through mini-cycles from time to time. For that reason, include nitrite testing as part of your monthly testing routine. Any elevation of nitrite levels is a red flag that indicates a problem brewing in the tank. If a fish is ill, or dies, it's wise to test for nitrite to ensure it is not contributing to the problem. The only way to reduce elevated nitrite levels quickly is via water changes.