Measuring NO3 level Share Facebook Twitter LinkedIn Pinterest E-mail In the aquaponic cycle, ammonia is converted to nitrite by nitrosomonas bacteria. When the nitrite level in the water reach a certain point, other bacteria, nitrobacter, convert nitrite to nitrate, which are less harmful to the fishes. Where was this made?: PH-testing of the water and discussion on water heating, Mediamatic Fabriek, Van Gendthallen