Nitrate is the final oxidation product of ammonia and nitrogen. It does not directly harm microorganisms such as fish and shrimp in water, but excessive accumulation will form old water, and it is easy to breed bacteria and algae. The water quality can be easily deteriorated. Generally, it can be controlled. 10 mg / liter or less. And if using Aquarium Pure, this aquarium filter media can remove the nitrate and nitrite apparently.