Why Test?
Nitrite, or NO2, is probably second in importance in pond water chemistry only to ammonia. The first group of bacteria to develop in the pond convert ammonia into Nitrite. As soon as Nitrite is present in the pond, the second group of important beneficial bacteria begin to colonize whose function is to convert the very toxic Nitrites into the pretty much non-toxic Nitrates. The problem with this is that Nitrites are much more toxic to fish than the ammonium was, and it takes 2-6 weeks for enough of the right bacteria to grow to be able to deal with the pond's Nitrite load. Once the biofilter is fully established, the nitrites are almost immediately converted to non-toxic nitrates.

View the MSDS Information for the testing solution and the Nitrite Test Kit Instructions.

Nitrite reading should be zero in any well established pond. In a newly established pond, nitrite levels must be detected and dealt with. Problems with biofilter (clogging, undersizing, medications) can result in the presence of nitrites even in an established pond. Adding too many fish at one time can also cause sudden increases of nitrites. Very low levels of nitrite are sometimes found in ponds in the deep south when the summer sun warms the water temperature into the 90's thereby inhibiting the bacteria.

Nitrite toxicity can be particularly deadly, usually resulting in the smaller fish dying before the larger ones. Severe damage is done to the gills, liver, spleen, kidneys, and even the nervous system of the fish. Concentrations as low as 0.25 ppm can kill small fish and levels of 0.5 ppm are considered an emergency and treatment indicated. Levels of 1ppm or higher is an extreme emergency which requires immediate action.

Use Liquid Clear to make your nitrite levels balance out.
Use a Master Test Kit to test for all problematic areas.