Calcium reactor

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A calcium reactor is a system for supplying seawater aquariums with the necessary minerals.

The calcium reactor was invented in 1991 by Rolf Hebbinghaus. Rolf Hebbinghaus works at the Löbbecke Museum in Düsseldorf and has been head of the seawater department there since 1989. There he was faced with the problem of supplying the inhabitants of a large reef aquarium with all the necessary trace and macro elements. R. Hebbinghaus' idea was to bring the elements bound in the construction of biomass back into solution. The small polyp stony corals are the main organisms involved in reef structure. They absorb various trace elements (e.g. strontium , iodine, etc.) and macro-elements ( calcium , magnesium, etc.) from the surrounding water and bind them into a firm limestone skeleton on which they can then continue to grow. This lime skeleton is formed via a so-called precipitation reaction, i.e. This means that the macro-elements mentioned are stored in the coral tissue until they reach a saturation concentration and then precipitate as a solid, crystalline structure: the calcareous skeleton. In order to supply the living corals with all the necessary elements, Rolf Hebbinghaus had the obvious idea of ​​solving the skeletons of dead corals and making them usable again for the living corals. Normally the firm structures of the coral skeletons are inseparable in the slightly alkaline seawater. However, experiments showed that at pH values in the acidic range, i.e. below pH 7, the calcareous skeletons are dissolved and their constituents are thus available again. Since it is of course not possible to lower the pH value of a saltwater aquarium below pH 7, the task was to develop a closed system in which fragments of coral skeletons are exposed to an acidic water environment in order to dissolve them.

functionality

Schematic representation of a calcium reactor, one of the most common methods of calcium supply in the reef aquarium to this day

In a closed reaction chamber, fragments of coral skeletons (broken corals) are loosened by lowering the pH value by adding CO 2 . This reaction chamber is fed drop by drop with water from the aquarium and mixed with the supplied CO 2 and acidified by internal circulation . The water that escapes is then enriched with the dissolved ions of the previously bound elements and drips back into the aquarium. The inside of the reaction chamber should have a pH of about 6.0 to 6.5 in order to achieve the best possible solution. The supplied CO 2 is fed in on the suction side of the circulation pump, dispersed by the impeller of the pump (broken into small bubbles) and then fed into the reaction chamber via the pressure side. The suction-side connection of the circulation pump should be connected at the highest point of the reaction chamber in order to take up again the unreacted CO 2 that collects there and feed it back into the reaction chamber.