SPS Coral

Small Polyp Stony (SPS) corals are reef-building corals known for their small individual polyps, rigid calcium carbonate skeletons, and often intricate branching or plating growth forms. SPS corals belong to the order Scleractinia and are among the primary architects of natural coral reef structures.

SPS corals are highly valued in reef aquariums for their coloration, growth patterns, and the structure they create within a reef system. Many species form branching, tabling, plating, or encrusting colonies that can grow into complex reef formations over time.

Common examples of SPS corals include Acropora, Montipora, Seriatopra, and Pocillopora. Growth rates and care requirements can vary significantly between species, even among corals within the same genus.

Most SPS corals thrive in stable reef conditions with temperatures between 76–79°F, salinity around 1.025–1.026 specific gravity, and a pH between 8.1–8.4. Alkalinity is commonly maintained between 8–9 dKH, calcium around 400–450 ppm, and magnesium between 1250–1400 ppm. Because SPS corals deposit calcium carbonate skeletons rapidly, consistent calcium, alkalinity, and magnesium levels are critical for healthy growth and skeletal development.

SPS corals generally prefer cleaner water conditions and lower nutrient levels than many LPS or soft corals. Nitrate levels around 1–10 ppm and phosphate levels between 0.02–0.08 ppm are commonly maintained in SPS-dominated systems. While ultra-low nutrient systems were once heavily emphasized, modern reefkeeping has shown that many SPS corals benefit from measurable nutrients provided overall system stability is maintained.

Most SPS corals require moderate-to-high lighting and strong, turbulent water flow. Proper flow helps deliver oxygen and nutrients to coral tissue while preventing detritus accumulation around the colony. Healthy SPS corals often display strong polyp extension, vibrant coloration, and steady skeletal growth under appropriate conditions.

Excessive direct flow can damage tissue or prevent polyp extension, while insufficient flow may allow detritus buildup and reduce gas exchange. Similarly, unstable or inadequate lighting can lead to browning, tissue loss, or reduced growth. Species such as Acropora often demand very stable conditions and intense lighting, while some Montipora and Seriatopora species may adapt more readily to a wider range of aquarium conditions.

Although SPS corals are often considered more demanding than LPS or soft corals, many species can thrive in captivity when provided stable parameters, appropriate lighting, strong water movement, and long-term consistency. Researching the specific needs of each species remains essential for successful SPS coral husbandry.