Salifert Nitrate (NO3) Test Kit (Reef)When an aquarium has insufficient regions deprived of oxygen (= anaerobic zones) or denitrification proceeds incompletely then nitrate will build up. A too high nitrate concentration can result in unwanted algae growth and these might irritate corals in their neighborhood. Nitrate as such also retards coral growth. The nitrate concentration in a proper functioning reef aquarium should preferably be lower than 1 mg L. Fish only aquariums would usually