Growing coral involves cultivating these fascinating marine invertebrates in controlled environments. This cultivation extends beyond personal aquariums, playing a role in broader ecological efforts like reef restoration, where cultured corals can help repopulate damaged natural reefs. The process requires a detailed understanding of their specific needs and a commitment to maintaining a stable aquatic habitat.
Understanding Coral Types for Cultivation
Corals cultivated in aquariums fall into three main categories, each with distinct characteristics and care requirements.
Small Polyp Stony (SPS) Corals
Small Polyp Stony (SPS) corals, such as Acropora and Montipora, have intricate, often branching structures and small polyps. These corals demand stable water parameters, intense lighting, and strong water flow, making them more challenging for beginners.
Large Polyp Stony (LPS) Corals
Large Polyp Stony (LPS) corals, including Favia and Euphyllia, have larger, fleshy polyps and a robust calcium carbonate skeleton. They tolerate a wider range of conditions than SPS corals, requiring moderate lighting and flow, which can make them more approachable for those new to coral keeping.
Soft Corals
Soft corals, like mushrooms, leathers, and zoanthids, lack a rigid stony skeleton, instead having flexible, fleshy structures. Soft corals are hardy and less demanding, deriving much energy from photosynthesis but also benefiting from occasional feeding. Their adaptability makes them a suitable choice for novice aquarists.
Setting Up Your Coral Environment
Establishing a suitable habitat for coral growth begins with selecting the right equipment. An aquarium tank forms the foundation; larger tanks offer greater stability in water parameters. Proper lighting systems are necessary, as photosynthetic corals rely on light. LED lights are chosen for their efficiency and spectrum control. Water circulation pumps, or powerheads, are essential for simulating natural ocean currents, delivering nutrients to corals, and removing waste.
A robust filtration system, including a sump and protein skimmer, maintains water quality. Heaters or chillers ensure water temperature remains within the ideal range, 24-27°C (75-80°F), preventing stress and coral bleaching.
Maintaining precise water parameters is fundamental for coral health and growth. Salinity, the salt concentration, should be 1.023-1.026 specific gravity or 32-35 parts per thousand (ppt). Consistent temperature is important to prevent stress.
Alkalinity, measuring the water’s buffering capacity, should be 8-12 dKH, as it supports coral calcification and stabilizes pH levels. Calcium, 400-450 ppm, is used by stony corals to build their skeletons. Magnesium, 1200-1350 ppm, helps regulate calcium and is important for skeleton formation.
Techniques for Coral Propagation
Coral propagation, referred to as “fragging,” involves creating new coral colonies from existing ones. This process helps manage coral size, expands collections, and supports conservation efforts by reducing demand for wild-caught specimens. Fragging stony corals involves cutting a “frag” from a larger “mother” colony.
For Small Polyp Stony (SPS) corals like Acropora, bone cutters or coral clippers snip a branch, aiming for a clean, precise cut to minimize damage. Large Polyp Stony (LPS) corals, like Euphyllia, require bone cutters, a Dremel, or fragging saw to cut through their thicker skeletons between polyps. Soft corals, including mushrooms and zoanthids, propagate by cutting a section with sharp scissors or a scalpel.
After cutting, the coral frag attaches to a frag plug or small piece of live rock using reef-safe super glue gel or epoxy. It is important to work quickly and keep the coral hydrated in tank water during the process to minimize stress. Sterilizing tools before and after use prevents pathogen spread. Placing the newly fragged coral in an area with appropriate light and flow for healing is important.
Ongoing Coral Care
Maintaining a healthy coral environment requires consistent attention to routine tasks after initial setup and propagation. Regular water testing monitors parameters like temperature, salinity, pH, alkalinity, calcium, magnesium, nitrates, and phosphates. Weekly testing is recommended, especially for alkalinity and calcium, which corals consume.
Routine water changes, 10-20% of the tank volume weekly or bi-weekly, remove accumulated waste and replenish trace elements. Proper feeding strategies vary by coral type; LPS corals can be target-fed meaty foods like brine or mysis shrimp, while SPS corals benefit from planktonic foods. Soft corals benefit from photosynthesis and occasional broadcast feeding.
General tank cleanliness, including cleaning algae from glass and vacuuming the substrate, prevents detritus buildup that can negatively affect water quality. Observing corals for signs of stress, such as discoloration, tissue recession, or changes in polyp behavior, is important for early detection. Maintaining stable water parameters and proper nutrition are preventative measures against disease and stress.