How to Test for Calcium in a Reef Aquarium

In the article you will find some basic information on How to Test for Calcium in a Reef Aquarium. Calcium is one of the most important parameters to monitor in a tropical reef aquarium. The easy-to-use and very accurate Salifert test kit is the industry standard.

To measure for calcium in a tropical reef tank with the Salifert Calcium Profi-Test, the aquarist need only follow these simple instructions. It is essential to remember that the chemicals used to perform the test can be dangerous and should only be used with extreme caution.

What’s in the Salifert Calcium Profi-Test Kit?

The Salifert Calcium Profi-Test Kit contains two syringes, a test tube (or test vial), a test tube cap with a small plastic spoon attached, and three bottled substances labeled Ca-1 (a powder in the smallest bottle), Ca-2 and Ca-3 respectively. There is also a plastic tip for the smaller of the two syringes. The aquarist will notice that the smaller syringe has graduations of 0.01 ml marked on it.

Preparation

Before performing the test, the aquarist will first want to rinse the syringes and test tube with water from the reef aquarium that is to be tested. This ensures that any residue from previous tests is removed prior to the current test. After discarding the water with which the syringes and test tube were rinsed, the aquarist is ready to begin the test.

Step One – Mix a Spoonful of Ca-1 Powder into the Sample

The first step is to add 2 ml of aquarium water to the test tube (the larger syringe is marked for 2 ml). It is now necessary to open the smallest bottle, which is labeled Ca-1. Using the spoon attached to the test tube’s top, the aquarist carefully adds a single spoonful of Ca-1 to the aquarium water sample in the test tube.

Recap the bottle of Ca-1 and place it aside.

Step Two – Add the Ca-2 to the Sample

Next, the aquarist will open the bottle labeled Ca-2, and add exactly eight drops of Ca-2 to the aquarium water sample in the test tube.

Recap the bottle of Ca-2 and place it aside as well.

Cap the test tube and gently agitate the sample for at least ten seconds.

Step Three – Fill the Small Syringe with Ca-3

After securely fitting the plastic tip onto the smaller syringe, the aquarist will open the bottle labeled Ca-3 and draw 1 ml of the Ca-3 solution into the syringe. The aquarist will note that even though some air will be present beneath the plunger, the syringe will have exactly one ml in it when the black part of the plunger is equal with the 1 ml mark on the syringe.

Recap the bottle labeled Ca-3 and place it aside.

Step Four – Observe Color Change to Blue

The aquarist now opens the test tube and adds one drop of the Ca-3 solution from the small syringe to the aquarium water sample and swirls the test tube for a couple of seconds. He or she then adds another drop and swirls the sample again for a period of a couple seconds, while carefully watching for the water to change color from pink to blue.

When the aquarium water sample in the test tube turns blue, the aquarist will recap the test tube and place it aside.

Step Five – Calculating Parts Per Million of Calcium in the Aquarium Water Sample

Looking closely at the small syringe with the remaining Ca-3 solution in it, the aquarist records the position of the black part of the plunger in terms of the 0.01 ml markings on the syringe.

To calculate the calcium level of the aquarium water in parts per million, the aquarist simply subtracts the number recorded on the syringe from the number one and then multiplies the result by 500. In other words:

• ppm Ca = (1 – reading in step 6) x 500

Most reef aquarists aim to keep their calcium level steady somewhere between 380 and 450, which means that the reading taken on the syringe should fall between 0.24 and 0.10.