Product:
Nitrates are harmful and undesirable chemical compounds in aquarium, resulting from a biological decomposition process that comes from fish or invertebrate waste substances such as feces, urine and excess food. 
While fish are much better able to handle nitrate in their water than ammonia, too much nitrate can still be toxic.

Want to reduce the nitrates in your aquarium?

• Adding live plants,
  Plants naturally utilize nitrate as a nutrient and food. This is why persistently high nitrate usually results in an algae outbreak and green aquarium water problems. An abundance of nitrate is fuel for explosive growth of existing algae cells.

• Lesser fishes,
  Fish waste results in an increase of nitrate levels. Keeping your fish population low helps prevent nitrate build up by reducing the amount of fish waste produced, and by lessening the chance and amount of uneaten food in the tank.

• Reduce feeding,
  This goes in line with having lesser fishes.
  Too much fish food, or fish waste will over pollute the water and result in high nitrate levels.
  Reduce the amount of feed entering the tank would directly improve the situation.

• Water changes,
  Water changes help remove nitrates and replace the aquarium with fresh water. And can be a good way to instantly reduce the amount of nitrates. Do however, still test your water source to know its parameters.

Instructions:

• Add 2ml of aquarium water into the test vial.
• Add 4 drops of the NO3-1 to the test vial. Swirl gently for 10 seconds.
• Add 1 spoon of the NO3-2 powder to the test vial. Swirl for 30 seconds.
• Wait for 3 minutes before placing the test vial against the color chart.

Typical nitrate value to strive for should be within the range of 4 – 20mg/L of Nitrate.

Note:
Keep out of the reach of children! Only for aquarium hobby use.
The use of protective gloves and eye protection is recommended.
Please read the instructions carefully before using the product. 

Salifert:
Salifert is a Netherlands base company that produces top of the line test kits as well as tank additives and foods for marine and reef aquariums.
Salifert is well established and popular with hobbyist for their accurate and affordable test kits.