The TetraPond Ammonia test kit allows for simple and accurate measurement of ammonia in your pond.Fish waste, uneaten food and dead plants in your pond are decomposed during the nitrogen cycle. The decomposition of this waste first produces ammonia, ammonia turns to nitrite and finally the nitrite turns to nitrate. If the ammoina levels in your pond are above 0.25 mg/l for extended periods of time this is harmful to fish.High levels of ammonia are also an indication that your biological filtration system is not working correctly.Includes 25 Tests