Salifert Nitrite Profi-Test is designed to detect nitrites, which can become toxic to fish and invertebrates if the biological cycle breaks down. Many nitrite test kits struggle with amine interference, resulting in inaccurate readings--especially when nitrite concentrations are low. Salifert's kit avoids this problem while providing complete color development in one minute and intense, easily-detectable shades. It features two scales--ultra-low (0.002 to 0.12 mg/L) and medium (0.02 to 1.2 mg/L)--which make identification of nitrite easier. Good for 50 tests, it works with marine, fresh, and pond water, and displays results in either ppm nitrite or ppm nitrite-nitrogen (multiply the reading by 0.3). For higher sensitivity, hold the test vial against a white chart and divide the readings by 10.