The Calcium Checker HI758 from Hanna Instruments is a device which can be used to measure calcium levels in your aquarium. It has a natural presence in all water sources due to deposits of gypsum, dolomite, limestone etc. It is a necessary component for animal and plant nutrition, but excessive levels can cause pipe or tube scaling. Using this simple checker you can get reading with an accuracy at 25 degrees Celsius of +/-6% with a range between 200 and 600 ppm. This precision is due to each instrument being dedicated to a single parameter which eliminates the chance of contamination.

All handheld colorimeters from Hanna Instruments have the advantage of combining quality with affordability. Previously, the only options for calcium readings were chemical test kits that were cheap but inaccurate and professional instrumentation that was expensive and hard to use. These checkers provide very precise readings, are very affordable and only use one button to operate.

In order to get an accurate reading you need to follow a few steps. First, you need to zero out the instrument by adding a vial with the water sample and reagent A and then pressing the button. After that take it out, add reagent B and shake the vial. After the reagent has dissolved you can place it in the checker again and press the button once more for the reading.

The Calcium Checker HI758 only weighs 64 grams so it is easy to carry around with you in case you need to provide readings away from home. The big LCD display uses large digits in order to show clear results. The auto shut off feature works after 10 minutes of inactivity. The checker requires one AAA battery in order to work. Included in the standard kit are 2 sample cuvettes with caps, reagents for 15 tests, battery and instructions.