Marine Magnesium Checker HC Handheld Colorimeter – HI783

The HI783 Marine Magnesium Checker HC is a handheld colourimeter that uses the Beer-Lambert principle to determine the concentration of magnesium colourimetrically. The HI783 is designed specifically to measure magnesium levels in saltwater aquariums or marine biology applications. The 1000 to 1800 ppm range is ideal for coral/fish or fish-only aquarium maintenance.

  • Ideal for aquariums and marine biology
  • Easier to use and more accurate than chemical test kits
  • Small size, big convenience


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The Hanna Marine Alkalinity (dKH) Checker® bridges the gap between simple chemical test kits and professional instrumentation. Chemical test kits have limited accuracy and resolution since they rely on the human eye to discern differences in colour. Professional instrumentation incorporates a light source such as an LED or tungsten lamp with a filter and a light sensing detector to precisely determine absorbance and ion concentration. This level of instrumentation also offers greater resolution and accuracy but can cost hundreds of dollars. The Hanna Marine Alkalinity Checker® measures alkalinity in dKH units, using a fixed wavelength LED and silicon photodetector to provide the accuracy of professional instrumentation at the affordable price of a chemical test kit.


Features at-a-glance:

  • Easier to use and more accurate than chemical test kits
  • Dedicated to a single parameter
  • Small size, big convenience
  • Ideal for: Aquaculture & Aquariums, Water Quality



Range0.0 to 20.0 dKH
Resolution5 ppm
Accuracy±5% of reading @ 25 °C
MethodAdaptation of the colourimetric EDTA method using calmagite indicator. The reaction between magnesium and the reagents causes a blue to violet tint in the sample.
Light sourceLight Emitting Diode @ 610 nm
Light detectorSilicon photocell
Environment0 to 50 °C (32 to 122 °F); max. 95% RH non-condensing Prepared sample cuvette (sample plus reagents) must be 18 to 28 °C (64 to 82 °F).
Battery type1.5V AAA Alkaline
Auto shut-offAfter 10 minutes of non-use
Dimensions86.0 x 61.0 x 37.5 mm (3.4 x 2.4 x 1.5”)
Weight64 g (2.3 oz)
InterferencesCalcium below 300 ppm and above 500 ppm


HI783 Checker HC is supplied with:

  • Sample cuvette and cap (2 pcs.)
  • Marine Magnesium reagent starter kit (reagents for 25 tests)
  • 1 mL graduated syringe and tip (1 pc.)
  • 5 mL syringe and tip with black printing (1 pc.)
  • 5 mL syringe and tip with blue printing (1 pc.)
  • 1.5V AAA Alkaline battery (1 pc.)
  • Instruction manual
  • Quick-reference guide.

Additional information

Weight.37 kg
Dimensions19.5 × 12.5 × 6.5 cm


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