Why Test? Within your aquarium, fish waste together with uneaten food and dead fish (or plants) are decomposed in a process known as the Nitrogen Cycle. This cycle involves the decomposition of fish waste etc. into ammonia, ammonia into nitrite, and nitrite into nitrate. Nitrate is continually produced by an established, fully functioning biological filter. Nitrate levels over 50 mg per liter can be harmful to your fish and encourage unsightly algae growth. This kit is professionally developed to accurately determine the nitrate level in your aquarium water. Shipping weight: 1/4 lb.