Cobalt

Essential trace element in minimal traces. Component of vitamin B12. Important for bacteria and algae, monitored with ICP.

Detailed explanation

Cobalt is a trace element found in natural sea water at concentrations of approximately 0.01-0.05 ug/l. It is the metal centre of vitamin B12 (cobalamin), essential for many metabolic processes.

Nitrogen cycling bacteria and microalgae need trace amounts of cobalt for their metabolism. In the aquarium the quantity needed is so small that sea salts and water changes provide it without problems.

Excess cobalt is rare but possible with overdose of trace element supplements. At high concentrations it can become toxic.

In freshwater aquariums cobalt is included in some plant fertilisers as part of the micronutrient mix. Does not require separate dosing.

ICP analyzes measure cobalt but in aquarium practice it almost never requires specific interventions. If the value is out of range, a water change with good quality salt almost always solves the problem.

Reference values by aquarium type

How it is measured

Only via high sensitivity ICP-OES analysis.

What happens when it is too low

Practical effects rarely observed in aquariums.

What happens when it is too high

Possible toxicity from overdose of supplements.

Related terms