Hanna Instruments Alkalinity Checker Review(The Definitive Guide)

Hanna Instruments Alkalinity Checker Review


hanna instruments alkalinity checker review



This is the ultimate review of the Hanna Instruments Alkalinity Checker.

In this comprehensive guide I will cover:

  • Packaging and included equipment
  • How to use the checker step by step
  • Analyzing the results
  • And much more


For anyone keeping a reef tank, you know how important it is to maintain a constant level of alkalinity. Most hobbyists who keep SPS coral successfully will tell you that alkalinity is the most important water parameter to monitor and maintain.

The main functions of alkalinity in your saltwater tank are:

  • Maintain PH or acidity
  • Provide carbonate and bicarbonate

Your corals are constantly pulling alkalinity out of the water which is used to build their coral skeletons. Coral calcification depends on proper levels of alkalinity as they absorb it. When corals consume carbonate alkalinity it reduces the amount of carbonate available to other corals and reduces the overall alkalinity, raises acidity and lowers PH.

The rate of alkalinity depletion depends on a few factors:

  • Tank size
  • Size of the corals
  • Growth rate


If you have a larger tank that is fully stocked with stony corals, you will need to supplement the tank more often in order to keep your water at the proper levels.

In this case, the alkalinity will drop more rapidly versus a smaller tank with just a few corals in it.

It’s true that performing frequent water changes will help replenish the alkalinity levels in your tank when using the proper salt mix. But most likely this will not be enough to fully replenish and you will need to dose your tank with an alkalinity supplement on top of regular water changes.

The best ways to add alkalinity back into your tank are dosing and using a calcium reactor which will produce alkaline water.

It’s important to check the alkalinity level of your aquarium on a regular basis. The proper level for alkalinity is between 8-12 dkh.

The most important factor is to maintain the level that works for your tank and corals. Don’t chase numbers. Prevent them from fluctuating up and down.



It’s crucial that the Alkalinity level in your tank remains within this range. There will be health issues for your fish and corals if the alkalinity gets too low or too high. Both will lead to problems and even death of your livestock can occur.

So in order to prevent this from happening, you need to use a quality test kit that will give you accurate results.

Today, I will show you my review of the Hanna instruments alkalinity checker with step by step instructions on how to use it properly. I have been using this test kit for a few years and it’s my trusted source for testing alkalinity in my reef tank.

If you are in a rush, you can check out the Hanna alkalinity checker on Marine Depot here.


hanna alkalinity checker review




Hanna Instruments Alkalinity Checker Review


The Hanna alkalinity checker is a compact electronic colorimeter used for testing alkalinity in saltwater aquariums. A colorimeter is a device that compares the amount of light waves that go through a test solution with the amount of light that penetrates a reference solution. In aquariums, we use sample water and a reagent for that.

The electronic colorimeter is a very precise way to measure your water levels versus a standard aquarium test kit where it can be difficult to read color charts that are not very accurate.


Features and specs chart:


hanna alkalinity checker review
Credit: Marine Depot



The Hanna Alkalinity checker comes well packaged and includes everything you need. It includes a solid storage case with clips to hold it shut protecting the equipment inside.

When you open the case you will see the contents of the HI755.  This includes:


  • Colorimeter supplied with one AAA battery

    The colorimeter is identical to the other Hanna devices, the only difference is the color. The alkalinity checker is blue. The LCD screen shows the test result and there is a hinged door on top that opens to insert the test sample. The door requires you to squeeze lightly in the center to open it.

    The single AAA battery is accessible by opening the bottom cover using a Phillips screwdriver. Everything in the kit is solid and of great quality.


Hanna Instruments Alkalinity Checker

Hanna Instruments Alkalinity Checker



  • Two glass cuvettes with screw tops



Hanna Instruments Alkalinity Checker


  • 1mL marked syringe


Hanna Instruments Alkalinity Checker


  • 30ml bottle of reagent solution HI755S suitable for 25 tests


Hanna Instruments Alkalinity Checker


  • Laminated, splash-proof instruction card


Hanna Instruments Alkalinity Checker



Hanna Instruments Alkalinity Checker



Using The Hanna Alkalinity Checker Step By Step


Using the Hanna Alkalinity checker is quite simple. There are a few steps you need to follow but they are simple steps to complete.

Basically you are going to complete 3 main steps.

  1. Power on the checker. Wait for C1 to be displayed. Fill the cuvette to the 10 ml mark with aquarium water to be tested.
  2. Insert the sample water into the checker and press the button. C2 will now be displayed.
  3. Add 1ml of the reagent to the cuvette. Invert a few times to mix. Place back into the checker and press the button. Read the results on the screen.

Let’s dive into these steps a little further in more detail.

When you first press the power on button, all the segments will be shown on the screen. Within a second, this will change to Add C1 with the word “press” blinking. This shows that the meter is ready.


Hanna Instruments Alkalinity Checker


Next, carefully add aquarium water to the cuvette making sure you only fill to the 10 ml mark. Don’t allow water to get on the sides of the cuvette and avoid fingerprints. Replace the screw-on cap. Insert the test tube into the checker and close the lid.


Hanna Instruments Alkalinity Checker


Now press the button on the checker. The display will now show Add C2 with “press” blinking.


Hanna Instruments Alkalinity Checker


Open the lid of the checker and remove the sample. Unscrew the cap and carefully add 1ml of the HI 755S reagent using the included syringe.

Hanna Instruments Alkalinity Checker

Hanna Instruments Alkalinity Checker


Replace the cap and gently invert the sample 5 times. Now place the cuvette back into the checker and close the lid.

Hanna Instruments Alkalinity Checker review


It’s important to not spill any of the reagent as the full-color development may be inhibited giving the wrong reading.

Press the button on the checker. You will now see the exact alkalinity concentration measurement on the screen. This will be shown in ppm or dkh. The normal range for alkalinity is 8-12 dkh. To convert ppm to dkh, simply multiply by 0.056.


Hanna Instruments Alkalinity Checker review


So depending on the Hanna checker you have, you will either have the result shown in ppm or dkh. In the example above, my alkalinity checker is in ppm and showing 176ppm which is 9.85dkh.




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Analyzing the results – Accuracy


Hanna Instruments shows accuracy @ 25°C/77°F is ±5 ppm (mg/L) or ±5% of reading, which is highly accurate.

Remember the normal range for alkalinity is 8-12 dkh. Adjust your aquarium dosing schedule accordingly to maintain a constant level within this range.

A few important notes about using this test kit. You have to make sure the cuvette is clean and free of any residue on the inside and also free of fingerprints and smudges on the outside. This can affect the path between the LED and light detector and may show inaccurate test results.

One of the great things about the Hanna checkers is by using an actual electronic microchip machine, we can eliminate human error by misreading color charts and graphs. Other hobby test kits can be easy to use but reading the results can be difficult.

The problem with misreading the results especially on color charts is the fact we will make changes to aquarium water that are not necessary causing more harm than good.


Should you buy the Hanna Instruments Alkalinity Checker?


In my opinion, the Hanna test kits are a very reliable and accurate way to check your aquarium alkalinity level. They are my number one recommended testers on the market today.

It will allow you to make the necessary adjustments for your tank keeping your corals healthy and vibrant.

Also, they are affordable and provide great value. Not only is the quality great, but you will be able to complete 25 tests initially with the kit. The upfront cost will be more than other test kits on the market.

For example, you might pay $45-50 for the Hanna kit for 25 tests and only $15-20 for another brand like Seachem or Salifert and get 75-100 tests.

But the value comes in when you need to buy replacement reagents. Once your 25 tests are used up, you can buy replacement reagents for $8-10. With other brands, you most likely need to buy another full kit. So the upfront cost is more, but that will balance out and you will be on the plus side and saving money in the long run.

Also, consider the quality of the test kits. The Hanna checkers are superior to others and in my opinion well worth the initial cost. I have used most of the other brands on the market, and while some do a great job, they just can’t compare to the Hanna test kits.


You can check today’s price of the Hanna Alkalinity checker on Marine Depot here.

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