Nitrites are usually converted into nitrogen gas via a sufficient filtration system, however if left unchecked, levels can cause fish and plant health problems as well as promote algae growth.
This Nitrate Test Kit from Salifert is part of their excellent range of test kits that are designed to help you pinpoint problem areas in your aquarium. This kit of 50 tests is very sensitive, to provide the most accurate, intense results possible.
Results are visible in just one minute, so you can quickly check nitrite levels and act accordingly. The kit has two separate scales, one with a range of 0.002-0.12 mg/l, and another with a medium scale from 0.02 - 1.2mg/l.