The Complete Guide: How to Grow Coral in Your Home Aquarium

The vibrant colors and intricate structures of coral reefs are a source of endless fascination. For many aquarium enthusiasts, the dream of recreating a piece of this underwater paradise at home is a compelling one. While it might seem daunting, successfully growing coral in a home aquarium is achievable with the right knowledge, patience, and dedication. This comprehensive guide will walk you through each step, from understanding the basics to mastering the finer points of coral husbandry.

Understanding Coral: The Building Blocks

Before diving into the practicalities, it’s crucial to understand what coral actually is. Corals are marine invertebrates belonging to the class Anthozoa. They are colonial animals, meaning they consist of many tiny individual polyps that live together and secrete a hard calcium carbonate skeleton. These polyps have a symbiotic relationship with microscopic algae called zooxanthellae, which reside within their tissues. These algae provide the coral with vital nutrients through photosynthesis, while the coral provides the algae with shelter and compounds they need for photosynthesis.

There are two main categories of corals relevant to home aquarists: Stony Corals (SPS and LPS) and Soft Corals. Understanding the differences between these is vital:

• Stony Corals (SPS – Small Polyp Stony Corals): These corals, like Acropora and Montipora, have hard, calcified skeletons and are generally considered more challenging to keep due to their high demands for water quality and lighting. They are characterized by small polyps and often form branching or encrusting colonies.
• Stony Corals (LPS – Large Polyp Stony Corals): These corals, like Brain corals, Favias, and Euphyllia, also have hard skeletons but feature larger, more visible polyps. They are often more forgiving than SPS corals but still require stable water parameters.
• Soft Corals: These corals, like Leather corals, Mushrooms, and Xenia, lack a hard, calcified skeleton and are typically easier to care for, making them suitable for beginners. They often sway gently in the current and come in various shapes and colors.

Essential Equipment for a Thriving Coral Reef Aquarium

Successful coral growth hinges on providing the correct environment. Here’s a breakdown of the essential equipment you’ll need:

• Aquarium Tank: A larger tank (75 gallons or more) is generally recommended, as it provides more stable water parameters and allows for more natural coral growth. A standard glass aquarium or a more advanced acrylic one will work.
• Filtration System:
  • Protein Skimmer: Crucial for removing organic waste before it breaks down into harmful nitrates.
  • Sump: An external tank placed below the main display aquarium. The sump will house most of the filtration and allow space for equipment. A sump is generally recommended for coral tanks.
  • Mechanical Filtration: Filter floss, sponges, or filter socks used to remove particulates. These should be cleaned or replaced regularly.
  • Biological Filtration: Live rock (porous rock that houses beneficial bacteria) and/or ceramic media that remove harmful ammonia, nitrites and convert them into nitrates.
• Lighting: Corals require intense lighting for photosynthesis. The type of lighting will vary depending on the type of corals you plan to keep. LEDs are the most efficient and customizable option, allowing you to adjust the color spectrum and intensity to meet the specific needs of your corals. For SPS corals you should aim for a PAR of 300-500 at the top of the tank and lower at the bottom. For LPS 150-300 PAR is generally adequate and soft corals can do fine with 80-200 PAR.
• Water Circulation: Powerheads or wavemakers are needed to create sufficient water flow, which helps distribute nutrients and removes waste products. It also ensures corals get adequate access to nutrients and prevents dead spots in the aquarium.
• Heater and Thermostat: A reliable heater and thermostat are vital to maintain a stable temperature, ideally between 76-80°F (24-27°C).
• Test Kits: Essential for monitoring water parameters like pH, alkalinity, calcium, magnesium, and nitrates.
• Salt Mix: Use a high-quality reef salt mix.
• Refractometer: Used to accurately measure salinity.
• Auto Top-Off System (ATO): Maintains a consistent water level, as evaporation can significantly alter salinity.
• Dosing Pumps (optional): Automated system for adding essential elements like calcium, alkalinity, and magnesium, especially important for SPS tanks.

Setting Up Your Coral Aquarium: Step-by-Step Guide

Once you’ve gathered your equipment, follow these steps to set up your coral aquarium:

1. Prepare the Aquarium:
   • Place your empty aquarium in a secure and stable location, away from direct sunlight and high traffic areas.
   • Connect your sump (if using), and plumbing.
   • Add a layer of aragonite sand to the bottom of the aquarium.
2. Install Filtration System:
   • Place your protein skimmer in the sump.
   • Add filter floss or sponges to your mechanical filtration section of the sump.
   • Add live rock to your display aquarium, making sure to leave ample swimming space and consider future coral placement.
   • If using, add your biological filtration media to the sump.
3. Fill with Water:
   • Mix your reef salt with RO/DI water in a separate container to your desired salinity using the refractometer (typically around 35ppt).
   • Use a powerhead in the container to ensure the salt mix dissolves properly.
   • Once the salt mix is fully dissolved, begin slowly filling your display aquarium and sump.
4. Install Lighting and Circulation:
   • Mount your LED lights above the tank and set to an appropriate intensity and spectrum for your chosen corals.
   • Place powerheads or wavemakers in strategic locations to create good water flow throughout the tank.
5. Cycle the Aquarium:
   • This crucial step allows beneficial bacteria to colonize the system and break down waste.
   • Add a small piece of fish food or an ammonia source to start the cycle.
   • Regularly test the water using your test kits to monitor ammonia, nitrite, and nitrate levels.
   • The aquarium is considered “cycled” when ammonia and nitrites are consistently at zero and nitrates are detectable. This can take several weeks.
6. Acclimate Livestock Slowly:
   • Once the tank is fully cycled, begin adding your first fish, inverts or corals slowly to prevent overwhelming the biological filtration.
   • Acclimate any new livestock by slowly introducing tank water to the bag they arrived in over the course of at least 30 minutes.

Coral Husbandry: Maintaining a Healthy Reef

Once your aquarium is set up, consistent maintenance is critical for coral health and growth:

Water Parameters

Maintaining stable water parameters is paramount. Here are the key parameters to monitor:

• Temperature: 76-80°F (24-27°C)
• Salinity: 35 parts per thousand (ppt) or 1.026 specific gravity
• pH: 8.1-8.4
• Alkalinity (dKH): 8-12 dKH
• Calcium: 400-450 ppm
• Magnesium: 1250-1400 ppm
• Nitrates: < 10 ppm (ideally close to 0 for SPS corals)
• Phosphates: < 0.05 ppm

Regular testing (at least weekly, or even more frequently for advanced systems) and water changes are essential for maintaining these parameters. If parameters begin to drift, then the correct chemicals or adjustments need to be made. Make small changes over time to prevent shocking your corals.

Lighting

Provide adequate lighting based on the specific needs of your corals. Monitor the growth and color of your corals and make adjustments as needed. Consider purchasing a PAR meter to ensure lighting is sufficient and consistent throughout the tank.

Water Circulation

Ensure adequate water flow to deliver nutrients, remove waste, and prevent dead spots. Adjust powerhead placement and settings as needed.

Feeding

While corals primarily receive nutrients from zooxanthellae, some corals also benefit from supplemental feeding. Target feed larger polyp corals with finely minced seafood or specialized coral foods 2-3 times a week.

Water Changes

Perform regular water changes (10-20% every 1-2 weeks) to replenish trace elements and remove accumulated nitrates and other unwanted compounds. Always use RO/DI water and a high quality reef salt mix.

Dosing Supplements

For tanks with high coral loads, dosing supplements like calcium, alkalinity, and magnesium may be necessary to keep these parameters stable. You can do this manually or via a dosing pump.

Regular Observation

Observe your corals daily for any signs of stress, disease, or pests. Early detection of issues can make a big difference in successful treatments.

Choosing the Right Corals

When starting out, it’s best to choose corals that are relatively hardy and easier to care for. Here are some good options for beginners:

• Soft Corals:
  • Mushroom Corals (Discosoma, Rhodactis): Very hardy and require relatively low light and flow.
  • Leather Corals (Sarcophyton, Lobophytum): Can be a bit more sensitive to changes but are typically easier to keep once established.
  • Xenia (Xenia): Easy to keep but can grow rapidly.
  • Green Star Polyps (Pachyclavularia): Very hardy and fast growing, but can spread quickly over rocks if not contained.
• LPS Corals:
  • Torch Coral (Euphyllia glabrescens): Moderate to high lighting with moderate flow requirements.
  • Hammer Coral (Euphyllia ancora): Moderate lighting and flow and easy to feed.
  • Bubble Coral (Plerogyra sinuosa): Needs lower flow and can be easier to feed.

As you gain more experience, you can gradually introduce more challenging corals like SPS corals, but it’s best to start simple and build from there.

Troubleshooting Common Issues

Even with the best care, problems can arise. Here are some common issues and solutions:

• Coral Bleaching: Caused by stress from poor water parameters, high or unstable temperatures or excessive light. Address the cause of stress, adjust lighting or water parameters as necessary.
• Coral Recession: Corals start to lose tissue typically from poor parameters. Ensure all parameters are within recommended range.
• Algae Growth: Can indicate excess nutrients or poor lighting. Ensure sufficient flow and make necessary water changes.
• Pests: Some pests can feed on corals. Inspect any new coral for parasites before adding it to the main aquarium.
• Slow Growth: Poor lighting, inadequate nutrients, or unstable water parameters can slow coral growth. Test and correct.

Coral Propagation (Fragging)

As your corals grow, you may want to propagate them (a process often called ‘fragging’). This involves taking a small piece of a larger colony and growing it into a new coral. Here is a general outline of the process:

1. Choose a healthy coral: The coral should be healthy and fully expanded and free of pests or signs of stress.
2. Gather equipment: Sharp scissors, bone cutters, or a Dremel tool with a cutting disc, coral glue or putty, and frag plugs are needed.
3. Cut the frag: Using your chosen tool, carefully cut or break off a small piece of the coral.
4. Attach the frag: Apply a small amount of coral glue or putty to a frag plug and place the frag onto it.
5. Place the frag: Place the frag in a suitable location in your aquarium, with appropriate lighting and flow.
6. Monitor the frag: Observe the new coral fragment, making sure it is recovering and adapting to its new spot.

Fragging can be done with most corals but the specific steps can vary between species. Ensure you do research based on the specific type of coral.

Conclusion

Growing coral in a home aquarium is a rewarding endeavor that requires dedication, patience, and a willingness to learn. By understanding the specific needs of corals, providing the right environment, and performing regular maintenance, you can create a thriving and beautiful reef aquarium. Remember that every aquarium is unique, and what works for one might not work for another. Don’t be afraid to experiment, learn from your mistakes, and most importantly, enjoy the process!