Hanna Instruments

HI736 Ultra Low Range Phosphate Checker PPB

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The Ultimate in testing for Phosphorus and easily converted to Phosphate PPM.  Hanna's ultra-low range phosphorus colorimeter brings you more precise technology from your typical chemical test kit.

  • Remove the human error from your testing
  • No need to count drop or titrate your sample
  • Detects color changes your eye cannot
  • No calibration required
  • Get east, quick and consistent results
  • Accurate and affordable
  • Cost efficient: Once you purchase the Checker, reagents are sold separately saving money long term



Features at-a-glance:


  • Most popular phosphate meter for reef aquariums.
  • To convert phosphorus ppb to phosphate ppm multiply the reading by 3.066 then divide by 1,000
  • Saltwater only, best for SPS dominant aquariums and low nutrient systems
  • Reads as low as 1ppb phosphorus or 0.003 ppm phosphate (reads in parts per billion phosphorus)
  • Reads as high as 200ppb phosphorus or 0.613ppm phosphate
  • Comes with 6 tests (reagent refills are Hanna HI736-25) 
Extra reagent can be found here



0 to 200 ppb


1 ppb

Accuracy @ 25°C/77°F

±5 ppb ±5% of reading

Light Source

LED @ 525 nm

Light Detector

silicon photocell


adaptation of the Standard Methods for the Examination of Water and Wastewater, 20th edition, Ascorbic-Acid method


0 to 50°C (32 to 122°F); RH max 95% non-condensing

Battery Type

(1) 1.5V AAA


after three minutes of non-use and two minutes after reading


81.5mm x 61mm x 37.5mm (3.2" x 2.4" x 1.5”)


64 g (2.25 oz.)

In the box

HI736 Checker® is supplied with (2) sample cuvettes with caps, phosphorus ULR reagent starter kit for 6 tests (6 powder reagent packets), battery, instructions and quick start guide.


1 year limited warranty