Scandium in a Marine Aquarium and its Importance

Table of Contents

What is SCANDIUM (Sc)?

Scandium (Sc, Latin: scandium) is a silvery-white metal which is covered with a slightly yellow layer of scandium oxide in air. It belongs to the group of transition metals*. It occurs in the Earth’s crust and is dispersed throughout the Earth in the form of mainly gadolinite, euxenite and thortveitite minerals.

Scandium forms chemical compounds in which it occurs most often in the +III oxidation state: scandium hydroxide; Sc(OH)3, scandium oxide; Sc2O3 or as compounds with halides e.g. ScF3. Scandium oxide (Sc2O3) is very soluble in water to form scandium hydroxide, according to the following chemical reaction (1):

Sc2O3 + 3H2O →  2Sc(OH)   (1)

Importance of scandium in seawater

Scandium does not appear to have any biological role in living organisms. However, it is a metal that, at higher concentrations in seawater, can have negative effects on marine animals. Its presence in a reef tank is indicative of its contamination with this element.

Risks of excess scandium in seawater

High levels of Scandium in seawater are undesirable, although its effects on marine animals are not known.

How to protect the aquarium?

Scandium should be monitored regularly and kept at a non-detectable level of 0 μg/L. The absence of scandium in the seawater ensures healthy animals and beautiful colouration.

The most accurate and reliable method for determining scandium is ICP-OES analysis. The Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique is the most accurate analytical method for analysing the elemental composition of seawater.


In order to ensure the correct level of scandium in your aquarium you should test it regularly and ensure that it is at the correct level.

If scandium levels are above 0 µg/l, this can lead to health problems in corals and other animals and even death. The most common reasons for exceeding the recommended scandium level:

  • contaminated salt,
  • metal elements containing this element are known alloys of scandium with magnesium.

Find and eliminate the cause of the problem and lower the value of this parameter in the water. Carry out up to 6 water changes. It is recommended to change about 15% of the aquarium water volume during each water change until the recommended value of this parameter is reached. The water prepared for the change must have the correct target salinity level. Use salts with the correct parameters and composition suitable for the ICP test.

*Transition metals – a group of chemical elements in the periodic table, including side groups of the periodic table, i.e. groups 3-12.


About author

Picture of Magdalena Metzler

Magdalena Metzler

Privately, I am a mother and a lover of nature and sport. My main interest is quantum chemistry, which hides a whole lot of unsolved mysteries and connections, which is extremely exciting from a scientific point of view.
In my scientific career, I have conducted international projects focused on innovative solutions for many branches of business, e.g. automotive, construction, and now, of course, marine aquaristics.
Working at Reef Factory gave me a passion for marine aquaristics, which I can develop every day, building a chemistry department and creating products that will help aquarists take care of tanks and ensure the highest safety of animals. One of the most exciting memories of working at Reef Factory is the commissioning of the ICP-OES spectrometer, which analyzes the elemental composition of seawater. The method of analysis in ICP is based on an analytical technique, which is a combination of my passion for quantum chemistry and marine aquaristics.
I hope you find my articles on ReefPedia interesting and helpful! Happy reading :))