How to Manage Calcium in a Marine Aquarium

Calcium is Essential for Coral and Calcareous Algae Growth

Nov 3, 2008

It is important to raise the calcium level in a new marine aquarium to a level that will support calcium-dependent organisms. Here is how to achieve optimal results.

Maintaining appropriate levels of calcium in a tropical marine aquarium is critical to the health of corals, other animals and even some plants. Stony corals and calcareous algae (the “good” pink, purple and red algae) depend on the aquarist’s ability to maintain calcium at a level near or above what is found in natural seawater. While an acceptable target range for calcium is anywhere between 380 and 450 parts per million (ppm), it is best for the reef aquarist to shoot for 420 and 500 ppm.

How to Test for Calcium

The first step to maintaining appropriate calcium levels is to know the current calcium level in a given marine aquarium. Like many of the parameters marine aquarists, calcium levels are most commonly measured with a commercially available test kit. At present, the Salifert Calcium Profi-Test Kit is the industry standard. It is easy to use and very accurate.

Raising Calcium

There are a number of ways to raise calcium levels in a marine aquarium. The article “Calcium and the Saltwater Aquarium” discusses the use of Kalkwasser, a calcium reactor and a two-part additive. All of these methods are sound calcium solutions. There are also several products on the market that do not fall into any of these categories, but which are also worth considering as a means of raising calcium levels in a tropical marine aquarium.

For example, the all-natural Fiji Gold Coral and Live Rock Supplement quickly raises calcium levels (as well as other trace elements) without the risk associated with non-natural additives and supplements. The most important aspect of raising calcium in a tropical reef aquarium is to consistently use the same product or approach for a long enough period to assess its effectiveness.

Monitoring Calcium Levels in a New Marine Aquarium

The only way to assess a particular product or approach for raising calcium in a saltwater aquarium is to monitor the calcium level in the aquarium once the target calcium level is reached. Stability is the lynchpin of successful marine aquarium-keeping, and the reef aquarist should aim to keep the calcium level as stable as possible within the target range.

With a new saltwater aquarium—especially a reef aquarium—the aquarist should test for calcium at least twice a week until he or she is confident the calcium level has stabilized with whatever calcium maintenance product or approach is being employed. It is important to keep in mind that a new saltwater aquarium will often not be stable for at least six to nine months. While there are many ways to test for calcium, including the new electronic Pinpoint Calcium Monitor™, the most reliable way to monitor calcium in a new marine aquarium is to use a traditional test kit.

Monitoring Calcium Levels in a Stable Marine Aquarium

Once the aquarist is confident the aquarium is stable—and that it remains so while using whatever calcium-raising product or approach the aquarist has chosen to employ—it is common and acceptable to reduce the frequency with which one tests for calcium. Instead, the experienced reef aquarist uses daily observations to indicate if the parameters are stable within the target ranges (e.g., no new algae blooms, coral recession, etc.).

In certain situations, however, it is important to resume the twice weekly monitoring of calcium with a calcium test kit. These situations include:

The copyright of the article How to Manage Calcium in a Marine Aquarium in Saltwater Fish is owned by Ret Talbot. Permission to republish How to Manage Calcium in a Marine Aquarium in print or online must be granted by the author in writing.