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By Kenneth Wingerter
Given their exotic forms and intense coloration, it’s not difficult to understand the appeal of live corals for reef tanks. Indeed, many aquarists—especially marine aquarists—at least consider acquiring corals at some point.
The “difficulty level” of different coral species varies considerably; even so, most experienced reef aquarists would agree that successfully maintaining any type of coral over the long-term requires a certain amount of skill and diligence.
Thus, to ensure an enjoyable first-time experience as a coral keeper, it might be wise to start out with those types of coral that are known for being a bit sturdier and a lot more forgiving.
Tips for Maintaining Corals in a Reef Tank
No coral (or any aquarium animal, for that matter) is imperishable. Before we get to the really fun part—selecting some of your first aquarium corals—let’s be sure that your fish aquarium system is truly ready to serve as their next happy, healthy home.
Providing a Coral-Friendly Captive Environment
Prior success with marine fishes does not necessarily equate to guaranteed success with corals. These are very different creatures with their own unique husbandry requirements. Most notably, as a rule, corals are comparatively more exacting in their demands with respect to water chemistry and lighting. These two factors will have to be considered carefully before the very first coral specimen is purchased.
Getting the Water Right
Corals are particularly sensitive to ammonia and nitrite. Short, mild spikes of ammonia or nitrite concentrations might go unnoticed in a fish-only tank, whereas they can cause extensive mortality in any reef tank.
The only way to be sure that your nitrogen cycle is in good order is to inoculate the system with live nitrifying bacteria and test these parameters repeatedly to ensure that they remain below detectable levels.
The first part is especially straightforward: just add the appropriate amount of a quality inoculant, such as Dr. Tim's Live Nitrifying Bacteria. Then, over the course of the next three to four weeks, perform a daily analysis using a dependable test kit such as the API Saltwater Aquarium Master Test Kit. It includes tests not only for ammonia and nitrite but also for high-range pH and nitrate.
It should be safe to proceed after both ammonia and nitrite levels have remained below detectable levels for at least a couple of weeks. The pH level, which essentially is a measurement of the water’s acidity, is a critical parameter and should be between 8.3 and 8.4.
Nitrate, which tends to accumulate over time as the end product of the nitrogen cycle, should be below 10 parts per million (ppm). If either the pH or nitrate levels are off, you may simply perform water changes until they are within their acceptable ranges. Hereafter, these parameters (as well as ammonia and nitrite) should be checked on a weekly basis.
To maintain hospitable water chemistry for your corals over the long run, you’ll also need to test calcium, carbonate hardness (KH) and phosphate on a weekly basis. This can be accomplished using the API Reef Aquarium Master Test Kit.
Getting the Lighting Right
Now it’s time to consider lighting. By and large, the most trouble-free corals (and indeed all of the species described here) are zooxanthellate. This type of coral derives most of its nutrition from tiny, photosynthetic organisms called zooxanthellae.
Zooxanthellae live symbiotically within the coral’s body. Because they are photosynthetic, the symbiont (and therefore its host, the coral) requires intense lighting of a proper spectrum. This need can be fulfilled using a specialty reef aquarium lighting system such as the Current USA Orbit Marine IC LED system.
Aside from using a power light source, you can maximize the amount of light your corals receive by maintaining good water clarity; this is easily achieved with the Kent Marine Reef & Fish Tank Clarifier.
Just remember that tropical corals enjoy brisk water movement and a water temperature of 72-78°F. Having met these final criteria, you are indeed ready to begin shopping for your first corals.
Here are some of the different types of coral for reef tanks that are great for beginners:
1. Star polyps (Pachyclavularia spp.)
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These are the perennial first-timer favorites. Not only is this species attractive and virtually indestructible (some call it a coral weed), but it is inexpensive and widely available. While different strains vary slightly in appearance, it generally consists of a cluster of star-shaped polyps that emerge from a rubbery purple mat. Because they proliferate rapidly, star polyps provide quick satisfaction to hobbyists looking for growth as an early measure of success.
2. Leather corals (Sarcophyton spp.)
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Usually larger and mushroom-shaped (especially the “toadstool” varieties), these make for nice centerpieces in the beginner’s reef tank. Though the base is typically an unremarkable light brown color, the tentacles can take on a bright green hue. Occasionally, the tentacles will retract for long periods of time, during which the base may become coated with a waxy substance. Don’t worry when this happens, as this is the coral’s means of cleaning itself. With proper water flow, this film will slough off and the tentacles will reemerge soon after.
3. Bubble coral (Plerogyra sinuosa)
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The bubble coral is among the most popular and certainly among the hardiest of the stony corals. It requires relatively little care provided that it doesn’t receive strong, direct water currents. Also, when handling this species, be sure to avoid brushing it against hard surfaces as to not tear its delicate polyps. Interestingly, at night, the bubbly polyps retract while longer, narrow tentacles expand to catch zooplankton prey. Because they tolerate subdued lighting, bubble corals may be positioned in lower or shadier parts of the tank.
4. Trumpet coral (Caulastrea furcata)
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Trumpet corals offer the newbie coral keeper a bit more color and pattern than many of the other tough coral species. While coloration can vary somewhat, this species is typically green or bluish green in the center of each large, puffy, trumpet-shaped polyp. While the edges are of a less intense brownish color, they frequently bear attractive, white radiating lines. Moreover, the skeleton exhibits a beautiful branching form. Trumpet corals require moderate to brighter illumination, but are much more tolerant of polluted water than other stony corals.
5. Open brain coral (Trachyphyllia geoffroyi)
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This coral consists of a single, huge, fleshy polyp on a rather small skeleton. It is perfectly happy to rest over the substrate on the very bottom of the tank and is indeed quite tolerant of lower light levels. Aside from its physical and physiological resilience, it is favored for its bright coloration. Most often, it takes on a deep red color that is especially impressive under bluish lighting. Though this stony coral is zooxanthellate, it will gladly accept an occasional (and surprisingly big) bite of food; for this, a meaty item such a single large krill will suffice.