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Coral Reffs
by John Somers
Physical Geology
Spring 2008


Coral Reefs


                    Coral Reefs contain some of the most vibrant and colorful animals on the planet. The corals which compose a reef system vary in shape, texture, color and share a commonality in that the entire reef is alive. It is difficult to fully understand the complexities of a coral reef, since the reefs are located in remote locations and underwater. One of the best ways to examine a coral reef is by creating a coral reef in a marine aquarium. To illustrate how a coral reef is created I will be illustrating with the use of my home marine aquarium.

                The sun is the first and most important part of life on the planet. In order to simulate the intensity of the sun, this system uses two 400watt metal halide bulbs, one 175watt metal halide bulb and two blue actinic 160watt fluorescent tubes. This grouping of lights promotes algae growth in the corals, chlorophyll in the plants, zoochlorellae in invertebrates “anemones” and for the general health of the fish. The lighting system is on a timer which begins and ends the twelve hour lighting cycle with the actinic lights. Ultimately this combination of overlapping lights simulate the suns natural dusk to dawn cycle and intensity.


                In addition to the energy produced by the sun, coral reefs need a constant temperature to thrive. In nature, temperature fluctuations rarely change more than a couple of degrees, which is primarily due to the enormous volume of water in the oceans. Fluctuations in temperature caused by global warming could cause the oceans temperature to rise; the smallest variance in temperature could destroy an entire coral reef system. In order to maintain a healthy coral reef, it is critical to maintain a constant temperature, which would become difficult without the aid of an aquarium chiller. Aquarium chillers cool the water, while aquarium heaters warm the water maintaining a constant temperature.



                In order for corals to grow, they need to be supplied with calcium. Supplying an enclosed reef system with calcium can be problematic, since the larger the system becomes the greater the absorption rate of calcium within the system. In order to maintain calcium values greater than 500mg with carbonate hardness between 20 and 30dKH, the use of a calcium reactor should be used. The reactor allows water to circulate repeatedly over calcium carbonate (crushed sea shells), while being mixed with carbon dioxide gas within the diffusion chamber. Mixing the carbon dioxide within the diffusion chamber creates a pH level around 6.0, which can dissolve calcium carbonate producing calcium bicarbonate. The calcium bicarbonate produced by the reactor is easily ingested by the corals and invertebrates, which are converted back into calcium carbonate promoting skeletal and shell grow within the reef system.


                Lighting, temperature, calcium, salinity and nutrition are constants provided by the ocean waters surrounding coral reefs. The ocean water which supplies the coral reefs with nutrition also removes toxic levels of nitrite, nitrate, ammonia and protein. The filtration system used by the ocean to protect natural coral reefs can be simulated in aquariums to protect aquarium reef systems. Filtration in aquarium reef systems requires using porous media, which collects and colonizes a bacterium that consumes excess nutrients.  Protein or organic waste can be removed from an aquarium by using biological filtration. The use of a protein skimmer combined with an ozone reactor is an effective means of removing the majority of the hazardous materials which could damage a coral reef system.





The use of mangrove trees are also an effective means of removing waste
and excess nutrients.


                When aquarists create an aquarium coral reef system that is equal
to natural coral reefs, they can expect to raise similar corals.

Some examples of aquacultured corals raised in an aquarium coral reef
system are below.



Large Polyp Stony coral (LPS) Frogspawn Coral, florescent green with
pink tips. 
Water Conditions:
72-78° F, sg 1.023-1.025, pH 8.1-8.4, dKH 8-12


Large Polyp Stony coral (LPS) Aussie Blasto Coral, florescent green center
with pink rims.
Water Conditions
: 72-78° F, sg 1.023-1.025, pH 8.1-8.4, dKH 8-12



Small Polyped Stony coral (SPS) Acropora Coral, Green.
Water Conditions
: 72-78° F, sg 1.023-1.025, pH 8.1-8.2, dKH 8-12


Small Polyped Stony coral (SPS) Horn Coral, florescent green.
Water Conditions
: 72-78° F, sg 1.023-1.025, pH 8.1-8.4, dKH 8-12


Small Polyped Stony coral (SPS) Indigo Digitata Coral, yellow.
Water Conditions
: 72-78° F, sg 1.023-1.025, pH 8.1-8.4, dKH 8-12


Small Polyped Stony coral (SPS) Pocillopora Damicornis - Aquacultured, brown.
Water Conditions
: 72-78° F, sg 1.023-1.025, pH 8.1-8.4, dKH 8-12