Coralline algae
Pink-purple calcareous algae that encrust rocks and glass in marine aquariums. Sign of good health of the aquarium and natural competitors of unwanted algae.
Detailed explanation
Coralline algae (Corallinales) are red algae that deposit calcium carbonate in the cell wall forming a hard pink, purple or red crust. They are a positive indicator: their presence means that the water parameters are good.
To grow Coralline algae need: calcium above 400 ppm, KH 7-12, magnesium 1300-1400, moderate light (does not like direct bright light) and clean water with low nutrients.
Coralline algae compete with unwanted algae for space on rocks. An aquarium with good coverage of coralline algae has fewer problems with filamentous algae, cyanos and dinoflagellates. This is why many reefers actively encourage them.
To seed Coralline algae you can scrape off rocks with good coverage and distribute the fragments into the water flow. There are also commercial products (ARC Reef, Coralline Algae Algae in a Bottle) that contain Coralline Algae spores.
Coralline algae also grows on glass. Usually it is not an aesthetic problem on the rear glass but must be removed from the front with an aquarium blade. The blade must be steel for standard glass, plastic for acrylic.
Calcium and KH consumption of coralline algae can be significant in aquariums with lots of cover. It must be taken into consideration in the dosage of balling.
Coralline algae does not grow in new aquariums. Months of maturation and stable parameters are needed. Their appearance is one of the milestones that mark the maturity of a marine aquarium.
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