Concrete blocks for use underwater for algal culture.

摘要

A concrete block is provided with iron (II) or (III) sulfate on its surface, to neutralise alkali leached underwater from the concrete. The iron ions are also good for growth of algae and fish and shellfish. The sulfate is present either in crystals (4) embedded in recesses (2) in the surface of the block (1), or as a continuous layer on the surface, the layer being coated from a liquid mixture of iron sulfate particules and a surfactant. A single shaped block can serve as an artificial reef for growth of algae in a shallow sea zone; it may have recesses to shelter sea animals. Various assemblies of the blocks are described for culture of fish and animals.