In the uppermost water column the surface ocean is undersaturated with respect to dissolved silica, except for the Antarctic Circumpolar Current south of 55°S. The dissolved silica concentration increases with increasing water depth, and along the conveyor belt from the Atlantic over the Indian into the Pacific Ocean.

Theoretical computations indicate that the dissolution of silica in water proceeds begins with the formation of a SiO
₂·2H
₂O complex, which is converted to orthosilicic acid.

The biogeochemical silica cycle is regulated by the algae known as the diatoms.
 These algae polymerise the silicic acid to so-called biogenic silica, which is used to construct their cell walls (called frustules).
In the uppermost water column the surface ocean is undersaturated with respect to dissolved silica, except for the Antarctic Circumpolar Current south of 55°S. The dissolved silica concentration increases with increasing water depth, and along the conveyor belt from the Atlantic over the Indian into the Pacific Ocean.
Theoretical computations indicate that the dissolution of silica in water proceeds begins with the formation of a SiO
₂·2H
₂O complex, which is converted to orthosilicic acid.
The biogeochemical silica cycle is regulated by the algae known as the diatoms.  These algae polymerise the silicic acid to so-called biogenic silica, which is used to construct their cell walls (called frustules).
Orthosilicic acid