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Hanna Instruments Alkalinity Checker (HI772) - dKH


Item #: HN1190

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The Hanna Marine HI772 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.)
  • Uses Hanna Instruments Marine Alkalinity reagents HI772-26
  • 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
  • Manufacturer information

    Hanna Instruments USA Aquarium Supplies
    Hanna Instruments is a leading manufacturer of analytical aquarium instrumentation. They were founded in 1978 and are headquartered in Woonsocket, Rhode Island. When Hanna introduced pH Electronic Paper in 1986 it literally revolutionized the world of testing by allowing millions of people in various industries to test for pH in a simple, accurate and affordable way. Hanna employees are constantly challenging themselves to improve on existing technology and to invent new testing techniques with the common goal to simplify analytical testing. This applies not only to instrumentation, but also to sensors development, reagents and chemicals. Hanna also believes in controlling the quality of their products from inception to delivery so they manufacture everything themselves, from meters and electrodes to chemical reagents and buffer solutions.

    5 Stars


    Reviewed on
    February 16, 2021

    Yes, I would recommend this.

    Best Checker

    Pros: Easy to preform test

    Cons: none

    This is the best checker I've purchased. To me its the best checker to buy when starting out. Very easy to preform the test with digital readout. I test every other day to make sure my dosing pump is still running correctly and the tank isn't using up more than needed.

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    Reviewed on
    November 30, 2020

    Yes, I would recommend this.

    Great and easy

    Pros: Easy and fast

    Cons: None

    I use this every day to keep track of my dkh, and i love it

    Was this review helpful? 0 0


    Reviewed on
    November 28, 2020

    Yes, I would recommend this.

    Best in Class

    Pros: Dependable and ease of use

    I had this in the past...very easy to use...love digital readings will be buying one in the near future

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    Reviewed on
    November 26, 2020

    Love it

    Pros: compact, ease of use, digital display

    Cons: have to buy new reagents,

    This test kit is easy to use and accurate. Just a few steps and boom, your alkalinity is measured. The digital display leaves out the guessing.

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    Reviewed on
    August 11, 2020

    Yes, I would recommend this.

    Buy it

    Pros: Easy to use

    Cons: None

    Easy to use. Makes it a breeze to monitor an important parameter

    Was this review helpful? 0 0


    Reviewed on
    June 07, 2020

    No, I would not recommend this.

    False readings immediately

    Unit was 3.o higher than a Redsea test I ran on the same water. Indicat my water was 6.0 in a tank that has amazing growth. Cant trust these checks. Bough A Calcium and it had error codes to start off. Returning them for refunds! I'll stick with my RED SEA kits!

    Was this review helpful? 0 1


    Reviewed on
    June 06, 2020

    Yes, I would recommend this.

    Hanna Alkalinity Checker

    Pros: Easy to use. Easy to read display. No guessing.

    Cons: NONE

    This hobby/lab grade tester is always spot on. I often test twice just to make sure I am getting consistent results, and the results are almost always the exact same!

    Was this review helpful? 0 0


    Reviewed on
    May 19, 2020

    Yes, I would recommend this.

    Doesn't get any easier!

    Pros: Fast, simple and accurate!

    Cons: None!

    I love these colorimeters! The directions are simple and I love getting an actual number result. I am color blind and the traditional test kits kill me trying to figure out the result! I can get the result in less than 1 minute!

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    Reviewed on
    May 11, 2020

    Yes, I would recommend this.


    Pros: quick tester

    Cons: none

    great product and easy to test the water with this. just follow instructions

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    Reviewed on
    February 24, 2020

    Yes, I would recommend this.

    Makes a difference

    Pros: Accurate and easy to use

    Cons: You have to use the cuvettes but the more accurate reading makes it worth it

    Used Elos DKh for years ....changed to Hanna because the Elos was hard to find. Found my DKh was low and as a result my corals are looking better and growing better with DKh in a better range. Easy to use

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