Hanna Instruments Marine Calcium Checker® HC - HI758

  • $69.95
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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