Hanna Calcium Checker HI758

Hanna Instruments



SKU: 400000129112

Product Description

The Hanna Marine HI758U Calcium Checker® bridges the gap between simple chemical test kits and professional instrumentation, giving you accurate results for your saltwater aquarium in the palm of your hand.

Many test kits on the market today rely the human eye to judge and determine color changes, which are notoriously difficult to use, especially in the lower ranges. Many professional instruments offer great accuracy using technology, but are not affordable to the average aquarist. The Hanna Marine Calcium Checker® HI758U bridges the gap between simple chemical test kits and professional instrumentation, using 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 Benefit of Testing for Calcium


Calcium is an essential ingredient to a healthy and functional reef aquarium. Corals and coraline algae require calcium for calcification and growth, so much so that an aquarium stocked with these organisms require regular calcium supplements in order to maintain healthy levels.

A variety of commercially available supplements exist, from calcium salts to buffered calcium supplements, which raise both calcium and alkalinity. Many aquarists set up a regular supplementation schedule to maintain proper calcium levels. However, regular calcium monitoring is crucial to a healthy reef aquarium, even if such a system is in place. This is because as corals and coraline algae grow and mature, their requirements for calcium tend to increase. As a result, the growth of the aquarium might outpace the calcium supplementation regimen.

The ideal range for calcium in a healthy reef aquarium is between 380-450ppm. Values below 380ppm may slow the growth of corals, whereas high levels of calcium (>500ppm) puts the tank at risk for calcium carbonate precipitation (limestone formation).




  • The Checker HI758U easily fits into the palm of your hand or pocket
  • Ideal for Aquaculture and Aquarium testing
  • Easier to use and more accurate than chemical test kits
  • Large, easy to read digits
  • Auto shut off
  • Single battery operation
  • Use for quick and accurate on the spot analysis
  • Single button operation: zero and measure




Range 200 to 600 ppm
Resolution 1 ppm
Accuracy @ 25°C/77°F ±6% of reading
Light Source LED @ 610 nm
Light Detector silicon photocell
Method adaptation of the Zincon 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 81.5mm x 61mm x 37.5mm (3.2″ x 2.4″ x 1.5”)
Weight 64 g (2.25 oz.)
Ordering Information

HI758 Calcium Checker is supplied with:

  • (2) sample cuvettes with caps
  • Calcium reagent starter kit for 25 tests*
  • Dropper
  • 1 ml syringe with tip
  • 100 microliter pipette with tip
  • Plastic pipette
  • Battery
  • Instructions and quick start guide.
Warranty 1 year limited warranty

*Uses Hanna Instruments Calcium Reagent HI758U-26


How it works:

  • Press the button to power the meter on. Notice “Add C1” appears on the screen – you are now ready to begin testing.
  • Using the 1mL syringe, add 1mL of reagent A to the cuvette. Then, using the dropper, fill the cuvette to the 10mL mark with deionized water. Distilled water is also acceptable. Once the reagent and water are added, invert the cuvette five times to mix.
  • 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”, remove the cuvette from the meter.
  • Add 0.1mL of sample. For best accuracy, use the supplied 0.1mL pipette. Note: To use the Hanna Instruments Micropipette, first attach the pipette tip. Push the button to the first “stop”, and then immerse the tip into the sample. Slowly release the button to its original position. Then, wait two seconds to catch any drops before dispensing the sample into the cuvette to the second “stop”.
  • Once the sample is added, add one packet of reagent B to the sample. After that, cap the cuvette and shake vigorously for 15 seconds. Wait 15 seconds for bubbles to dissipate.
  • Wipe the cuvette of any oils and fingerprints, and place back into the meter. Press the button; The meter will directly display the concentration of calcium in ppm.


Calcium Checker Troubleshooting Tips

  1. Never rinse your cuvettes with tap water or saltwater
  2. Use pure vapor distilled water from your local pharmacy at C1 phase. RODI water from home filtration units may not be suitable for this test as calcium can easily permeate through your filter membranes.
  3. Clean your cuvettes with distilled or deionized water absent of Calcium that is going to be used for C1 phase dilution. 
  4. Measure out 9 ml of distilled or deionized water for C1 phase
  5. Make sure no excess aquarium sample saltwater is on the tip of the pipette. Only administer the saltwater that is sucked into the pipette tip. 


Manufacturer Info

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.

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