Seawater - Magnesium

Magnesium is necessary for the ion balance, and binds the silicic acid within the water. Many invertebrates and soft corals, sea fans, sea urchins, starfish and coralline algae need it to build their skeleton or shell.

The aimed (natural) magnesium content of salt water is approx. 1,350 (1,200 - 1,400) mg/l.

Possible consequences of a low magnesium content

• Stone corals and coralline red algae suffer from disturbances of growth
• Echinoderms show an insufficient skeleton and crayfish moulting problems

Identification

The difference between the total hardness (Ca + Mg) and the calcium content displays the current magnesium content.

Thereby 1° dH total hardness equals 0.179 mmol/l alkaline earth ions or converted 4.35 mg/l Mg or 7.17 mg/l Ca.