Nitrate is the waste product of naturally occurring bacteria (Nitrospira spp.) turning nitrite into relatively non-toxic nitrate. In a typical aquarium, nitrate is the final stage of nitrification and usually accumulates with time.

Why test for nitrate?
Invertebrates do not tolerate a high level of nitrate in a marine aquarium, so careful measurement is essential to keeping corals healthy. Nitrate is also the cause of many algae problems in a marine aquarium so monitoring and responding to nitrate can help reduce these algae issues.

What is the correct level of nitrate?
In a reef aquarium, a concentration of under 10 mg/l is optimal for both coral growth and health. In a marine fish-only system, nitrate should not exceed 20 mg/l. Higher readings are unlikely to affect fish health, but it may promote excess algae growth.

What to do if the nitrate level is wrong?
Regular partial water changes with a good quality salt should be sufficient in maintaining low nitrate. Good aquarium hygiene, such as removing excessive waste from filters or sumps will also help to keep nitrate down to a minimum. Excessive feeding will also cause high nitrate, so ensure that fish are not overfed.

How to test for nitrate?

• Add 5 ml of water to be tested into the test tube provided. The middle mark on the test tube indicates 5 ml.
• Ensuring reagent bottle 1 is closed, turn the bottle upside down and shake well for approximately 30 seconds to resuspend the catalyst particles.
• Immediately add 6 drops of Nitrate-1 reagent to the test tube. 4. Add 6 drops of Nitrate-2 reagent.
• Cap the test tube and shake well to mix.
• Wait for 10 minutes for the colour to develop.
• Once the 10 minutes has elapsed, view the test tube from the side and compare to the colour chart to determine the amount of nitrate present in the water.