Nitrite is produced continually during the ammonia cycle by nitrifying bacteria in the biological filter. While not as immediately toxic as ammonia, any accumulation of nitrite should still be addressed as soon as possible. The nitrite level will eventually be broken down to non-toxic nitrate. Regular testing for nitrite is recommended – chronic exposure to even low levels of nitrite can cause brown blood disease in fish, which can cause suffocation and death.

With the exception of a system establishing a biological filter and progressing through the nitrogen cycle, the nitrite level in any tank should ideally be zero.

To remove childproof safety cap, push down while turning.

1. Fill a clean test tube with 5 ml of water to be tested (to the line on the tube).
2. Add 5 drops from Nitrite Test Solution, holding dropper bottle upside down in a completely vertical position to ensure uniformity of drops added to the water sample.
3. Cap the test tube and gently shake several times to mix solution. Attention! Always use the cap. Avoid skin contact as this may affect the test results.
4. Wait five minutes for the color to develop.
5. Read the test results by matching the color of the solution against those on the Nitrite Test Color Chart.

To reduce nitrite: reduce feeding, perform partial water changes, add Fritz Complete water conditioner to neutralize any nitrite present, and add FritzZyme nitrifying bacteria.

In new aquariums, the nitrogen cycle commonly stalls when phosphate is limited and nitrite stop being converted to nitrate. If nitrite levels do not reduce, check the phosphate level with a Fritz Phosphate Test Kit. Typically, the addition of a phosphate supplement, phosphate-rich fish foods, or a water change with dechlorinated tap water will allow nitrifying bacteria to resume conversion of nitrite to nitrate.