Manganese

Essential microelement for aquatic plants and for some enzymatic processes in corals. Required in minimal traces.

Detailed explanation

Manganese is a microelement that participates in photosynthesis and various enzymatic processes. It is the second most important microelement for aquatic plants after iron.

In aquatic plants, manganese is involved in the photolysis of water (splitting of water during photosynthesis). A deficiency manifests itself with interveinal chlorosis on young leaves (yellowing between the veins that remain green), similar but distinct from iron deficiency.

In marine aquariums, manganese is present in natural water at approximately 0.2-0.5 ug/l. Its role for corals is marginal compared to other trace elements. Sea salts and water changes usually provide sufficient quantities.

In freshwater aquariums manganese is included in plant fertilisers (as part of the microelement mix). This is important in densely planted aquariums with bright light and CO2.

Excess manganese is rare and usually linked to tap water contamination or fertiliser overdose. Very high concentrations can be toxic to fish and invertebrates.

Measurement in marine aquariums occurs only via ICP. In freshwater aquariums it is almost never measured individually: it is assumed that a good complete fertiliser provides the necessary quantity.

Reference values by aquarium type

How it is measured

In marine aquariums only via ICP-OES. In freshwater aquariums, coverage by complete fertiliser is assumed.

What happens when it is too low

In freshwater aquariums: intervenous chlorosis on young leaves. Slowed growth of plants.

What happens when it is too high

Toxicity to fish and invertebrates at high concentrations. Rare in practice.

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