Reef Aquarium

Primarily, it's the presence of live rock. Live rock, as its name implies, is coral skeletons that have become inhabited by bacteria; micro and macro algae; worms; sessile invertebrates, like corals, anemones, sponges, crustaceans and other marine organisms. It serves as the building blocks for your reef, as well as fulfilling a number of other important functions. Most important is the biological function it performs. Live rock actually reduces organic wastes from the fish and other animals living in the aquarium. The coralline algae (pink, purple or red micro algae with calcareous or calcium-containing cell walls) absorb nitrogen and phosphorous just as live plants do in a freshwater aquarium. In addition, live rock is full of holes, tunnels and crevices. These provide perfect habitats for denitrifying bacteria. In the outside of the hole, aerobic bacteria perform the familiar nitrification process (which is the same in saltwater as it is in fresh, though with different bacteria species) of converting ammonia into nitrites, then nitrites into nitrates. Toward the back of the hole where oxygen has become scarce, denitrifying anaerobic bacteria complete the cycle, converting nitrates into nitrogen gas. In addition to providing habitats for your animals, plants and bacteria, live rock also introduces a wide variety of organisms into your tank. These provide a diversity of organisms that can serve as food to other reef inhabitants but mostly delight the aquarist as they are observed popping out of nowhere and growing into recognizable forms.

The obvious first step is to select a location for your micro-reef. It should be placed where it is easily viewed and readily accessible for feeding and maintenance. Direct sunlight should be avoided; it may cause undesirable algae growth on the acrylic and sudden spikes in water temperature. As mentioned above, any flat, sturdy surface that will support 75 pounds is perfect. This can be a dresser in the bedroom, a desk at work, the kitchen counter, or the top of a toilet tank. The easiest way to test whether the surface will hold the aquarium is to sit on it first. If it breaks, find another surface. If it doesn't, it's plenty strong.

The quality of the water used in the micro-reef is extremely important. The presence of organic chemicals, pesticides, chlorine, and fertilizers will assuredly ruin your hopes for a healthy reef in spectacular fashion. Similarly, traces of metals in the water like copper, iron, lead or mercury will destroy your invertebrates and likely your fish as well. While it might be assumed that the water is safe simply because it comes from the tap, a review of a printout from the local water company will probably be enough to warrant another source of water. It is probably wisest to use a de-ionization or reverse osmosis filter on the water to be used in the reef. If these are not available, distilled water can be purchased at the drug or grocery store. It's only a six- gallon tank, after all.

Two species of hermit crabs are appropriate for this system, Blue-Legged (Clibanarius tricolor) and Scarlet-Legged (C. digueti, also known as Red-Legged or Mexican Red-Legged) Hermit Crabs. Blue-Legged Hermits are easily identified by (no surprise here!) their blue legs with white and red bands at the joints. They are also somewhat smaller than their red cousins. Scarlet-Legged Hermits are easily identified by their astonishingly bright red legs. Their bodies are a pale orange or pink color. Hermit crabs are ubiquitous to all reef aquariums, barring only those that contain predators. A few moments watching them reveals why. Hermits are sufficiently entertaining to merit their own tank and look especially good featured in a small system. They scramble over the reef, daintily picking morsels from the rock while dragging their disproportionately large homes on their backs. You may periodically find "corpses". Before you despair an untimely death in the tank, realize that these are probably molts left behind by the growing Hermits. The addition of a few snail shells (usually available from the retailer that sold you the Hermits) may be a good idea to keep the little clowns from trying to evict a compatriot from its own shell as they grow out of their old ones. Hermits are excellent algavores and will also consume any uneaten food in the aquarium. In a six-gallon reef, as many as a dozen Hermits may be maintained, perhaps more, and the two species may be combined. Start by adding six or eight total. If a hair alga problem is evident, add more. Hermits usually cost two or three dollars each.

Maintenance of a micro reef should not be onerous and will become easy once a regular routine is established. Examine the aquarium's inhabitants on a daily basis. Note any differences in behavior, appearance and health of the animals. If an animal dies, whether mobile or sessile (non-moving), remove it immediately. Otherwise, the byproducts of decay will completely disrupt the balance in the reef and cause harm to the other animals. Take note of extraordinary algae growth and take appropriate measures (described below) if it continues unabated. Water loss from evaporation should be replenished periodically with fresh water (evaporation removes only water, not salt!). The water level should not be allowed to drop more than a half inch below the top frame of the aquarium. Otherwise, the salt level will rise and the splashing will leave salt deposits on the insides of the tank and hood. If there are fish, shrimp, crabs and other larger decorative animals in the aquarium, they will need to be fed. Feed a small pinch of general marine flake food three or four times a week. If there are Feather Duster worms in the tank, crush a flake or two into fine powder and add it to the reef. There should not be any noticeable amount of uneaten food about one half hour after feeding. Hermit crabs and shrimp will clean up most leftovers. Most reef inhabitants will appreciate periodic feedings of live or frozen brine shrimp, brine shrimp nauplii and Daphnia, if available. Daphnia and newly hatched brine shrimp are particularly good for cnidarians and Feather Duster Worms.