A clear guide to the key terms used in coral keeping and buying
Short for Small Polyp Stony — a category of hard corals with tiny polyps. Acropora and Montipora are representative species. They demand strong lighting and stable water parameters, making them suited for intermediate to advanced hobbyists.
Short for Large Polyp Stony — a category of hard corals with large, fleshy polyps. Brain corals and Open Brain corals are typical species. They are easier to keep than SPS and often display vibrant colors.
A general term for corals without a rigid skeleton. Zoanthids, Green Star Polyps, and Leather Corals are popular species. They tolerate water quality fluctuations well, making them beginner-friendly and relatively affordable.
A small piece cut from a mother coral colony. It is glued onto a small base called a plug and sold as a frag. Affordable and fun to watch grow, frags are ideal for beginners building a coral collection.
Microscopic algae that live symbiotically inside coral tissue. They supply nutrients to the coral through photosynthesis. When expelled due to heat stress or other factors, coral bleaching occurs. They also play a major role in coral coloration.
A device that uses fine bubbles to remove organic waste (such as proteins) from the water. It is essential equipment for marine aquariums, physically extracting dissolved organics that filters alone cannot eliminate.
A device that dissolves coral media with CO2 to replenish calcium and KH (carbonate hardness) in the tank. It is advanced equipment used when keeping many SPS or other calcifying corals that build limestone skeletons.
Natural porous rock colonized internally by bacteria and microorganisms. It handles biological filtration in the tank and provides hiding spots for corals and fish. It contributes to both aquascaping and water quality stability.
A measure indicating the salinity of seawater. For coral keeping, the ideal range is 1.023–1.025. It should be measured regularly with a hydrometer or refractometer, and top-off water added to compensate for concentration increases caused by evaporation.
A device that creates water movement inside the tank. Corals rely on flow to take in nutrients and expel waste. Adjusting the flow strength and direction to suit each coral species is key to maintaining their health.
A device that automatically dispenses precise amounts of supplements such as calcium, KH, and magnesium. It eliminates the hassle of manual dosing and keeps water parameters stable. Especially valuable for SPS coral keeping.
A filtration chamber installed below the main display tank in an overflow system. It houses equipment such as the protein skimmer and heater, and by increasing total water volume, it also contributes to water quality stability.