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reef fish

To keep your saltwater reef aquarium healthy, you want to maintain low nitrites (under 150 ppb) to ensure the health of fish and corals. It's important to test for nitrite when an aquarium is first being set up and when the tank is being cycled to make sure waste is being properly recycled. The easy-to-use Hanna Marine Ultra Low Range Nitrite Checker HC - HI764 generates accurate, digital readouts in parts-per-billion (ppb) versus trying to judge traditional nitrite test kit color charts.

Check Out the Hanna Nitrite ULR CheckerIn addition to being easy and accurate, the full line of Hanna Marine Checkers eliminate the hassle of always having to buy new test kits. When you run low on the supplied packets of HI764-25 reagent, just purchase a refill pack and you will be back to testing in no time.

How to Use the Hanna Marine Ultra Low (ULR) Nitrite Checker HC - HI764

Video: How to Use the Marine Nitrite Checker (3 minutes 40 seconds)


Note that the Hanna Marine Ultra Low Range Nitrite Checker HC - HI764 gives readings in parts per billion (ppb).

  • To convert the nitrite nitrogen concentration to the nitrite ion concentration in ppb, multiply the reading by 3.29.
  • To convert from ppb to ppm, divide by 1,000. 

Everything You Need to Start Testing

Our marine nitrite checker is supplied as a complete test kit and retails for $49. The kit includes:

Hanna Nitrite Marine Checker 




  • Hanna Marine Ultra Low Range Nitrite Checker HC - HI764
  • Two sample cuvettes with caps
  • Nitrite Ultra Low Range reagent starter kit
  • One AAA Battery
  • Water resistant case to store all testing items
  • The HI764 instruction manual and laminated quick reference guide. The reference guide includes the testing instructions and tips for accurate measurement. It’s the perfect companion to have while you are performing measurements.

How to test:

The Hanna Marine Ultra Low Range Nitrite Checker HC - HI764 is designed to make testing quick and easy.

  1. Press the button to power the meter on. When Add C1 appears on the screen, you are ready to begin testing.
  2. Fill a clean cuvette to the 10mL line with sample and fasten the cap.
  3. Using a micro fiber cloth, wipe the cuvette to remove any oils or fingerprints from the glass. Then place the cuvette into the checker and close the lid, making sure it is completely closed. It’s important to make sure that the lid is completely closed for an accurate reading.
  4. Press the button. Once the screen shows Add C2, remove the cuvette from the meter and add one packet of HI764-25 reagent.
  5. Fasten the cap, and shake gently for about 15 seconds until the powder is completely dissolved.
  6. Wipe the cuvette of any oils and fingerprints, and place it back into the meter.
  7. Press and hold the button until the timer is displayed on the screen. A six-minute countdown will begin.
  8. Once the timer reaches zero, the meter will display the concentration of nitrite nitrogen in parts per billion (ppb).

Hanna Marine Ultra Low Range Nitrite Checker Banner image

Why Test for Nitrite?

Many reefers and aquarists are aware of nitrite as a component of the nitrogen cycle. The nitrogen cycle begins when aquarium organisms produce ammonia as a toxic waste byproduct. From there, beneficial bacteria in the aquarium use the ammonia and convert it to nitrite, a less harmful byproduct. The nitrite is ultimately converted to nitrate by further oxidation from bacteria.

Nitrite is of biggest concern when an aquarium is first being set up and when the tank is being cycled.  Cycling an aquarium is the process of growing beneficial bacteria for the establishment of a bio-filter to support aquatic life.  Having the ability to measure nitrite in parts per billion (ppb) gives you a precise reading of their nitrite level that is not possible from most test kits, as well as a better understanding of whether or not their tank is cycled.  Regularly measuring nitrite is also needed to check the effectiveness of an aquarium’s bio-filter.  Adding new fish, overfeeding, and poor husbandry practices can all lead to stress on the aquarium’s biological filtration. 

In a healthy reef aquarium nitrite and ammonia are consumed by the bacteria, providing and maintaining a very low, steady concentration in an established reef tank. The ideal concentration of nitrite in a reef aquarium is less than 0.2 ppm or 200 ppb. Nitrite levels above this value may weaken sensitive fish and corals. The Hanna Marine Ultra Low Range Nitrite Checker HC HI764 is a compact and portable meter that measures from 0-200 ppb (µg/L), which is ideal for the range nitrite is found in established reef aquariums. 

The Limits of Traditional Color-Change Test Kits

Many test kits on the market rely on a color change that needs to be judged by eye. These are notoriously inaccurate and difficult to use, especially in the lower ranges. The Hanna Marine Calcium Checker HC - HI764 bridges the gap between simple chemical test kits and professional instrumentation. The one-button design makes testing for calcium a cinch to use.

Learn More About Our Full Marine Line of Checkers

And Don't Forget Your Nitrite Reagents!