What do corals eat??
This is a question that we should ask more often. Most corals are animals that live in symbiosis with tiny dinoflagellates called zooxanthellae. These dinoflagellate are chloroplast endowed that live under the coral tissue and produce sugars from photosynthesis, which are released for the benefit of their host. This makes the majority of corals to obtain their main nutritional sustenance just by placing them under a light source of appropriate intensity and spectrum.
But…is this enough? We note that the corals grow and live for many years in our aquariums eventhough we don't feed them any other way and tend to conform. Figure out that we suddenly start to feed ourselves with water and sugar, can we live like this? The answer is obvious: no, Although we will surely resist long. Well that's what happens to many corals when they reach an aquarium. Alright, maybe not so much, and I may be exaggerating because we can not compare the needs of a coral and a human, but you understand me, don't you?
Corals on the reef receive a nutrient flow, mainly zooplankton almost continuously; ocean currents carry this protein rich food from the colder waters to tropical reefs. This is something impossible to recreate in our aquariums, We can not toss zooplankton continuously without seriously impairing the water quality. But there are methods and practices that significantly benefit our aquarium corals, let's see what feeding mechanisms has a coral.
There is a third feeding mechanism: nutrient absorption.
A coral is able to absorb dissolved nutrients in the water through its tissue. And I do not mean only nitrogen compounds which greatly concern us (and so necessary although some hobbyists strive to rid them off the water), but also fatty acids, amino acids, vitamins…
Corals in the aquarium.
In some respects we can not imitate nature, it is not possible to maintain the macro nutrients flow continuously without affecting the water quality, but we can provide this food, as well as amino acids and fatty acids in controlled manner.
The benefits of feeding corals.
Hard corals' calcification rate on a healthy reef can reach 12 kgs of Ca(CO)3 per m2 and year (Kinsey, 1985). In the aquarium as a closed system will range between 0,5 and 6,5 kgs of Ca(CO3) per m2 and year (Carlson, 1999), but if the aquarium water is saturated above 9 ° dkH and is intensely fed they could reach 20 kgs of Ca (CO3) (Bingman, 1997)