Hanna Instruments - Checker Handheld Colorimeter Seawater Alkalinity (dKH)

Hanna Instruments - Checker Handheld Colorimeter Seawater Alkalinity (dKH)

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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 upon the human eye to discern differences in color. 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® uses a fixed wavelength LED and silicon photo detector to provide the accuracy of professional instrumentation at the affordable price of a chemical test kit.

The HI772 Checker®HC (Handheld Colorimeter) provides a simple, accurate and cost effective way to measure alkalinity in degrees of calcium hardness, commonly abbreviated as dKH. Critical to marine environments, alkalinity not only provides the carbonate ion required for calcium carbonate skeletal regeneration of coral reefs, but it also acts as a pH buffer against large changes in acidity. Designed as a more accurate alternative to chemical test kits, the HI772 provides quick, accurate results.

Why Test Alkalinity?

Alkalinity is the ability of a system to buffer the pH of a system as acids are introduced. In saltwater systems, alkalinity is present in two main forms; carbonate (CO32-) and bicarbonate (HCO3-). Alkalinity is a critical parameter to check for in aquaculture, especially in reef aquariums where drastic pH swings would be catastrophic to corals. Further, alkalinity is important to the calcification of corals. The ideal range for alkalinity in reef aquariums is between 125-200ppm of calcium carbonate (7-11 dKH). Many test kits are available on the market that rely on a color change that needs to be judged by eye. The HI772 from Hanna makes alkalinity testing easy by simply mixing the sample with reagent and pressing a button.


How it works:

The Hanna Marine Alkalinity (dKH) Checker® HC - HI772 is designed to make testing quick and easy.

  • Press the button to power the meter on. Notice "Add C1" appears on the screen. You are now ready to begin testing.
  • Fill the cuvette to the 10mL line with sample and fasten the cap.
  • Using a microfiber 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 is important to make sure that the lid is completely closed for an accurate reading.
  • Press the button. Once the screen shows "Add C2", extract 1mL of reagent from the reagent bottle with the syringe and add to cuvette. Once the reagent has been added, cap the cuvette and invert five times to mix.
  • Wipe the cuvette of any oils and fingerprints, and place back into the meter. Press the button, and the meter will display the alkalinity in degrees Karbonathärte (dKH).


  • Result in dKH - no conversion needed!
  • Compact, portable design
  • Built-in timer
  • One button operation
  • 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
  • Specifications:

  • Range: 0.0 to 20.0 dKH
  • Resolution: 0.1 dKH
  • Accuracy @ 25°C/77°F: ±0.3 dKH ±5% of reading
  • Light Source: LED @ 610 nm
  • Light Detector: silicon photocell
  • Method: colorimetric method
  • Environment: 0 to 50°C (32 to 122°F); RH max 95% non-condensing
  • Battery Type: (1) 1.5V AAA
  • Auto-off: after ten minutes of non-use
  • Dimensions: 86.0 mm x 61.0 mm x 37.5 mm (3.4" x 2.4" x 1.5")
  • Weight: 64 g (2.25 oz.)
  • Includes:

  • Hanna Marine Alkalinity (dKH) Checker HI772
  • 2 - sample cuvettes with caps
  • Alkalinity reagent starter kit for 25 tests (1 bottle of alkalinity reagent, 1 ml syringe and tip)
  • Battery
  • Instructions, and quick start guide