Hanna Instruments

Nitrate Low Range Colorimeter HI781 - Marine Water

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$49.45 $63.95

Discontinued by Bulk Reef Supply
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Easy and Accurate Nitrate Testing for your Saltwater Aquarium!

Get highly accurate results with the HI781 Marine Nitrate Low Range Colorimeter. With a digital read out, there is no more struggling to determine colors visually. This nitrate tester's compact design fits in your pocket or easily stores ina droor or testing bin with your other equipment. The test process is extremely easy and delivers guess-free results in just a few minutes.


Features at-a-glance:

  • For use with saltwater samples.
  • More accurate than chemical test kits.
  • Dedicated to a single parameter.
  • Small size, big convenience.
  • No errors with a digital readout.
  • Ideal for aquariums and marine biology applications.


The HI781 Checker is a simple, accurate, and cost-effective way to measure nitrate in your saltwater aquarium.

Nitrate is a by-product of the Nitrogen cycle. Excessive amounts of nitrates in a reef aquarium can promote the growth of undesirable organisms including algae and dinoflagellates while insufficient amounts can lead to starvation in which SPS and other corals will show signs including the loss of color and paleness.

The HI781 Nitrate Checker HC is a handheld colorimeter that uses the Beer-Lambert principle to determine the concentration of nitrate colorimetrically. The HI781 is designed specifically to measure low levels of nitrate in a saltwater aquarium.



  • Range: 0.0 to 5.0 ppm (as NO3-) / 0.0 to 50 ppm (calculated) using dilution
  • Resolution: 0.01 ppm
  • Precision: ±0.25 ppm ±2% of reading @ 77°F (25°C) / ±2.5 ppm ±5 of calculated reading using dilution
  • Light Source: LED @ 525 nm
  • Light Detector: Silicon photocell
  • Environment: 0 to 50°C (32 to 122°F); max 95% RH non-condensing
  • Battery Type: (1) 1.5V AAA
  • Auto-off: After 10 minutes of non-use and after read
  • Dimensions: 81.5 x 61 x 37.5 mm (3.4 x 2.4 x 1.5")
  • Weight: 64 g (2.25 oz.)
  • Method: Colorimetric method
  • Interferences: Nitrite, copper


More Information
UPC 200001099625
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Product Questions

Is this nitrate tester for salt water only.ta.daz
Question by: Darren on Jan 12, 2022, 11:27 PM
Yes, this is for Saltwater only.
Answer by: Matt Lucero (BRS Staff) on Jan 13, 2022, 10:39 AM
What is the nitrate range for the HI781 checker?
Question by: Glen Nile on Jun 28, 2020, 8:20 AM
Hi there!

Thank you for reaching out to us! Unfortunately Hanna has not made that information available yet.

Take care!
Answer by: Thomas Billington on Jun 29, 2020, 3:30 PM