A lot of my clients and readers have been having trouble with SPS corals lately, so I thought I would blog about what it really takes to keep these most-prized reef tank inhabitants thriving…
Why are SPS corals considered so demanding to keep?
SPS corals naturally grow in areas of the ocean like exposed reef flats that have consistent, strong sunlight, brisk water movement and stable water conditions, so these factors coupled with the need for large amount of calcium for skeleton building means these corals are not advised for the novice reef keeper:
– Water quality: must always remain high, with stable parameters (pH, specific gravity and temperature are most important here) and minimal concentrations of nitrates (less than 10 ppm) and phosphates (0 ppm). SPS corals will be the first to die if the water quality slips, way before any fish show any signs of discomfort. A good protein skimmer and efficient biological filtration including live rock will help with water quality in your tank
– Temperature stability: SPS corals especially Acropora species are the most sensitive species to temperature change, so the temperature needs to remain consistently stable. The best way to achieve this is with 2 smaller heaters, a good thermometer and a chiller if you live in a hot climate.
– Water movement: needs to be turbulent, SPS corals like anything from moderate to high water movement. This means big, powerful powerheads and pumps to create multidirectional water flow. Too little water movement often can kill SPS corals. If there is debris or slime on the corals the water movement is too little, basically you cannot have too much flow!
– Stress: these corals are easily stressed and can die if they have too little light and/or water movement, they can even get really stressed if you move them around the tank, so carefully place them once if possible! They need to be carefully and extremely gradually acclimated to your display tank.
– Lighting: SPS corals require intense, full spectrum lighting. This is best achieved with metal halides, VHO fluorescent, power compact or LED bulbs. When these corals are first placed in your tank, intensity should be dialled down for the first month, then after they have established it should be brought back up for maximum growth and reef building potential.
– Compatibility: to avoid antagonistic interactions in your tank SPS corals should be placed at least 3 inches away from other hard and soft corals, which may get annoyed at being rapidly outgrown and decide to attack with their sweeper tentacles! Avoid placing with crabs and other coral predators like bristle worms and mantis shrimp.
– Calcium levels: these corals need high levels of calcium (400 – 500ppm) and alkalinity best delivered with a calcium reactor (unless you have a tiny tank, in this case you can simply add to the water) to deliver the calcium in a usable format the corals can absorb. Strontium, Boron, Iodine and Iron are also important but regular water changes should take care of replenishing these trace elements, adding these as supplements can be risky in my opinion.
– Supplementary feeding : of SPS corals can be very beneficial to growth, although many think this is not necessary. Target feeding a SMALL amount of amino acid rich food such as plankton with a squirter will make a positive difference.
Good luck with your SPS corals!