Coral water refers to the specially prepared saltwater environment designed to support the diverse life forms found in coral reefs. This carefully balanced aquatic medium replicates the specific chemical and physical properties of natural ocean habitats where corals thrive. Maintaining these precise conditions helps ensure the health and growth of corals and other marine organisms within an enclosed system.
Natural Ocean Conditions for Coral Reefs
Reef-building corals flourish in warm, clear, and shallow tropical waters. These environments are characterized by stable temperatures, generally ranging from 73° to 84° Fahrenheit (23° to 29° Celsius). Corals also require saline water, typically between 32 to 42 parts per thousand, for optimal growth.
Sunlight penetration is important for many reef-building corals because they host photosynthetic algae called zooxanthellae. These algae provide corals with nutrients, explaining the preference for clear, shallow, sunlit zones. Coral reefs exist in environments with low levels of dissolved nutrients, a condition that helps prevent overgrowth by competing algae.
Essential Water Parameters for Aquariums
Replicating these complex natural conditions in an aquarium requires careful management of several water parameters. Salinity should be maintained between 1.023 and 1.025 specific gravity, or 35 parts per thousand. Consistent salinity is important, as fluctuations stress corals.
Water temperature in a coral aquarium should remain stable, between 75-80°F (24-27°C), to reduce stress and support coral health. Deviations can slow growth or lead to bleaching, where corals expel their symbiotic algae. The pH level should be kept between 8.1 and 8.4.
Alkalinity, measured in dKH, reflects the water’s capacity to resist pH changes. For a mixed coral tank, an alkalinity range of 8-12 dKH supports pH stability and coral skeletal formation. Calcium, used by corals to build skeletons, should be maintained between 380-450 ppm.
Magnesium works alongside calcium and alkalinity, preventing calcium carbonate precipitation and keeping these elements available for coral use. The range for magnesium is between 1200-1350 ppm. Regular testing and supplementation of these three parameters support healthy coral growth.
Managing Nutrients and Trace Elements
Managing undesirable nutrients like nitrates and phosphates is important for maintaining coral water. While some level of these nutrients is present in natural marine environments, their accumulation in aquariums can lead to excessive algae growth and negatively affect coral health. Nitrates, a byproduct of organic waste, and phosphates, often introduced through fish food, should be kept at low concentrations: nitrates below 10 ppm and phosphates near 0 ppm.
Strategies to manage these nutrients include:
Regular water changes, which dilute accumulated waste products.
Mechanical filtration, such as filter socks, to remove particulate matter.
Protein skimmers, which remove organic compounds, preventing their conversion into nitrates and phosphates.
Biological methods like refugiums with macroalgae, or chemical media like granular ferric oxide (GFO), to absorb excess phosphates.
Corals utilize various trace elements present in seawater, such as iodine, strontium, and potassium, for their biological processes. These elements are gradually depleted as corals grow and consume them. While regular water changes can help replenish these elements, advanced reef keepers may supplement specific trace elements based on consumption rates.