A frag rack is a perforated stand or tray used to hold multiple frag plugs upright and organized within a reef tank or dedicated frag system. It keeps growing coral fragments stable, visible, and easy to manage.

Specific gravity is a measurement comparing the density of aquarium water to pure freshwater, commonly used to express salinity. Reef tanks typically target a specific gravity range around 1.025 to 1.026, checked regularly with a hydrometer or refractometer.

Skeletal growth refers to the ongoing process by which scleractinian corals build and expand their calcium carbonate skeleton over time. It’s directly supported by stable calcium, alkalinity, and magnesium levels, and reflects overall coral health.

Zoanthids are colonial soft corals known for their vibrant colors and hardy, fast-growing nature, forming mat-like colonies of small polyps. They’re a popular choice for both beginner and experienced reef keepers alike, valued for covering rockwork.

Photosynthesis is the process by which the symbiotic algae living within coral tissues convert light into energy. This relationship provides corals with a significant portion of the energy they need for growth, metabolism, and overall health.

Zooxanthellae are microscopic algae that live within the tissues of many reef-building corals. Through photosynthesis, these algae produce energy that helps support coral growth, metabolism, coloration, and overall health.

Zooplankton are microscopic animals that drift through the water column and serve as one of the most important natural food sources for corals and many other reef inhabitants. Rich in proteins, amino acids, fatty acids, and other nutrients, zooplankton plays a vital role in reef nutrition.

Vitamins are essential organic compounds that support coral health, growth, metabolism, and overall biological function. Although required in small amounts, vitamins play a critical role in helping corals maintain normal cellular processes and respond to environmental stress.

Trace elements are minerals that corals and other reef inhabitants require in very small amounts to support growth, coloration, metabolism, and overall health. Although needed in tiny quantities, these elements play essential roles in many biological processes within a reef aquarium.

Torch corals are popular LPS corals known for their long flowing tentacles, vibrant colors, and dramatic movement in the aquarium. Through a combination of photosynthesis and feeding, torch corals obtain the energy and nutrients needed for growth, coloration, and overall health.

Target feeding is a coral feeding method where food is delivered directly to a specific coral using a feeding tool such as a pipette, turkey baster, or syringe. This approach allows reef keepers to provide nutrition precisely where it is needed while minimizing food distribution throughout the aquarium.

Symbiosis is a close relationship between two different organisms that live and function together. In reef aquariums, the most important example is the partnership between corals and zooxanthellae, where both organisms benefit from working together.

SPS corals, or Small Polyp Stony corals, are reef-building corals known for their small polyps, rigid calcium carbonate skeletons, and often vibrant coloration. They are highly sought after by reef keepers for their growth forms, colors, and ability to create stunning reef displays.

Soft corals are corals that lack the large rigid calcium carbonate skeletons found in SPS and LPS corals. Known for their movement, vibrant colors, and adaptability, soft corals obtain energy through both photosynthesis and feeding while adding motion and diversity to reef aquariums.

A refugium is a separate area of a reef aquarium system designed to support beneficial organisms, nutrient export, and ecosystem stability. Commonly used to grow macroalgae and cultivate copepods, a refugium helps improve water quality while creating a more natural reef environment.

Proteins are complex molecules made from amino acids that support coral growth, tissue development, repair, and essential biological functions. They are one of the most important nutritional components corals obtain through feeding.

A protein skimmer is a filtration device that removes dissolved organic compounds and waste from aquarium water before they break down into nutrients such as nitrate and phosphate. Protein skimmers help improve water quality, increase oxygenation, and support overall reef stability.

Potassium is an essential major element found in natural seawater that supports cellular function, nutrient transport, and overall coral health. It plays an important role in coral coloration, metabolism, and biological processes throughout the reef aquarium.

Polyp extension is the visible expansion of a coral's polyps and feeding tentacles. Reef keepers often use polyp extension as an indicator of coral activity, comfort, and feeding behavior, although it should not be viewed as the sole measure of coral health.

Plankton is a general term used to describe organisms that drift through the water column and cannot actively swim against currents. In reef ecosystems, plankton serves as a major food source for corals, fish, and countless other marine organisms.