Coral reefs

Ultimate Secrets To Saltwater Fish

Idiot Guide To The Marine Aquarium

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The accumulation of calcareous coral skeletons gradually forms reefs, of which the most famous is the Great Barrier Reef, stretching north-eastward from south Aus tralia for almost 2,000 km. It is the biggest structure of animal origin in the world! This ecosystem, one of the richest and most diverse in existence, is also fragile and constantly subject to attack. The last few decades have witnessed the destruction of some reefs, the coral being used to build houses, roads, and even airport runways! Obviously, aquarists have been accused of taking part in this pillage, which seems grossly exaggerated: the removal of corals from their natural habitat for the aquarium trade does occur, but it is negligible compared to other large-scale extractions. Furthermore, some species are protected by law and never reach hobbyists' tanks. Public marine aquariums can, on the contrary, make a contribution to the study of invertebrates. The aquarium of the Monaco Oceanographic Museum, for mm&mim

WHEN MUST CALCIUM BE ADDED?

Calcium is added when the concentrated measured is less than 400 mg/liter. There are tests on the market to measure the quantity of this parameter. Remember that the measurement of CH, in sea water, reveals the quantity of carbonates and bicarbonates. When this is less than 7°CH (128 ppm), it can be concluded that a lack of calcium carbonate is more than likely and steps should be taken to remedy this.

HOW TO SUPPLY CALCIUM TO A CORAL AQUARIUM

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Method 1

From the start, i.e. when you put the first water in, use cor mercial salts enriched in calcium. Then, add the same salts over the course of regular partial water changes, at the rate of 10% per week.

Some commercial salts are specially designed for marine invertebrates. •

Method 2

Use commercial products specially prepared to increase calcium levels. Method 3

Place a calcareous element, such as calcareous rock, or crushed and washed oyster shells, in the filter, and this will gradually release calcium. However, this method give rise to any rapid or significant increase in calcium levels. Method 4

Prepare a solution of slaked lime, Ca (OH)2, available in aquarium stores, at a rate of 1.5 g/liter. Pour in 1 ml of this solution per liter of sea water.

Proceed gradually, monitoring the pH constantly to ensure it does not rise above 8.5. Method 5

This is the most complicated, but also the most effective. Prepare two solutions:

- one of dehydrated calcium chloride (CaCI2, 2H2O) at a rate of 15 g/liter, which will provide the calcium;

- the other of sodium bicarbonate (NaHCO3), at a rate of 17 g/liter, which will provide the carbonates.

Then calculate the difference between a carbonate hardness of 130 ppm (7.2°CH) and the one measured in the aquarium. Multiply the result by the net volume of the tank, and divide the result by 10. This will give the amount of each solution required, in milliliters, to pour into the aquarium.

Example: for a tank with a net volume of 500 liters, with a carbonate hardness of 100 ppm (5.6°CH), the result is: Amount of each solution (in ml) = 500 x (130-100) + 10 = 1,500 ml. The following table gives you the required amount of each solution (in ml) for specific cases.

When adding calcium, the pH value must not rise above 8.5, regular control is necessary.

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Carbonate hardness measured Net vol. in ppm of tank, in liters

130

125

120

115

110

105

100

400

0

200

400

600

800

1,000

1,200

500

0

250

500

750

1,000

1,250

1,500

600

0

300

600

900

1,200

1,500

1,800

700

0

350

700

1,050

1,400

1,750

2,100

800

0

400

800

1,200

1,600

2,000

2,400

900

0

450

900

1,350

1,800

2,250

2,700

1,000

0

500

1,000

1,500

2,000

2,500

3,000

• The leather corals of the Sarcophyton genus will not tolerate being dose to Coelenterates highly prone to stinging.

In their natural habitat, Coelenteratesfeed onanimal plankton, but these are difficult to supply in an aquarium. •

example, is carrying out research in this field, using a 40 m3 tank containing several tons of corals, which are nurtured and bred. Until recently, raising corals on this scale in captivity was impossible, above all because of their very great sensitivity to nitrates (NO3-). Scientists solved this problem by allowing these nitrates to turn into nitrogen gas (N2), thanks to the anaerobic bacteria which survive at the bottom of the tank, where the oxygen levels are low. The nitrogen produced by the metabolism of these bacteria then passes into the atmosphere.

This complicated technique is beyond the reach of most aquarists, however experienced they may be.

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