Selenium is considered one of the most important of the essential trace elements, especially when caring for SPS corals. The biological functions of selenium have been increasingly clarified during recent years. This substance is an important component of enzymes. Selenium is also contained in selenocysteine, the amino acid in the active centre of the enzyme glutathione peroxidase. For this reason it plays an important role in protecting the cell membrane from oxidative destruction. This unusual amino acid, together with another amino acid complex, plays an important role in antioxidative defence mechanisms. This is especially important for SPS because they grow close to the water surface and are exposed to high radiation. Here, selenium helps to prevent oxygen damage to the cell membrane. When selenium is added, it is important that it is dosed in the correct organic compound and combination with vitamins. You will find the right mixtures for dosing in our Elementals Trace solutions.

What’s this:

Selenium is an essential trace element which shows its effect especially in the protection against oxidative stress at high light levels. Selenium also ensures stable cell walls and, in combination with vitamins, supports the absorption of nutrients.


Too high selenium values (from approx. 20 µg/l (0,26 caus partial damage and tissue detachment, too low values disturb growth and reduce light tolerance


Partial water changes or dosing element concentrates

Indicator species:

No specific species, but selenium deficiency is indicated by increased tissue transparency, light sensitivity and poor nutrient uptake

Value too high:

Reduce dosing, water change. Selenium slowly degrades in the system.

Value too low:

Coral vitality starting at 25 % of indicated dosage, Elementals Trace Se.

Variety chalcogen, semi-metal
Benefit Growth, colour, health
Default value 2–5 µg/l (0,26
Skill Level Red, only for experienced aquarists
Source Salt, Supply Systems, Coral Vitality
Available Coral Vitality, Balling Light System, Feed
Importance 1–6 5
Detection quality medium

Balling Light:

Selenium is supplied via Trace 3 in the Balling Light system. Coral Vitality is used in the following systems. With selenium, due to the detection limit of the ICP measurement it is possible that this substance cannot be detected in water, although the supply via the feed or additives used is sufficient. You should seek advice before direct dosing.

However, selenium should not be dosed thoughtless. Too high doses quickly become toxic and can cause damage. Selenium plays an important role in SPS corals for light protection and growth.

Oxidative protection means a stress reduction to the coral, which leads to better nutrients uptake and growth. It also plays a role in the sexual reproduction of corals. Without a sufficient supply of selenium, the formation of egg packages in the corals does not occur.


Selenium is very rarely used in products for marine aquariums. At Fauna Marin it is different, and the demand is met directly by the aquarium systems. Feeding plankton and frozen food such as clam meat supports supplying the aquarium with directly available selenium compounds.