What are the Basic Requirements for Keeping Corals in an Aquarium? Essential Tips and Guidelines

What are the Basic Requirements for Keeping Corals in an Aquarium? Essential Tips and Guidelines

As a coral enthusiast, you may be eager to replicate the beauty and wonder of natural coral reefs in your aquarium. However, corals are delicate creatures that thrive in specific conditions, and understanding the basic requirements for keeping coral in an aquarium is crucial for their survival and growth.

Several factors must be carefully managed to provide an optimal environment for your corals, including lighting, water movement, and consistent water parameters. In addition, maintaining the correct levels of salinity, alkalinity, calcium, and magnesium is essential, as well as keeping a close eye on the temperature of your aquatic habitat.

Before diving into the complexities of coral care, it’s crucial to have a solid grasp of these basic requirements. Doing so will create a harmonious and visually stunning aquatic environment that allows your corals to flourish and thrive.

Basic requirements for keeping corals in an aquarium
Aquarium Coral

Understanding Corals

Corals are marine invertebrates that form colorful and diverse underwater ecosystems in reef aquariums. Understanding the various types of corals and their basic requirements is essential to successfully keep them healthy and thriving in an aquarium environment.

Types of Corals

Corals can be broadly categorized into two main groups: soft and hard. Soft corals like mushrooms, zoanthids, polyps, and leather corals are popular among beginners and experienced aquarists alike because of their flexibility and ease of care.

Hard corals, on the other hand, are further divided into two types: SPS (Small Polyp Stony) and LPS (Large Polyp Stony) corals. These corals are often more challenging to maintain and have more specific requirements than soft corals.

Polyps and Zooxanthellae

Corals are made up of tiny, individual organisms called polyps that live together in colonies. Each polyp has a mouth surrounded by tentacles and is connected to neighboring polyps. Some popular aquarium polyps include green star polyps, button polyps, bubble corals, and toadstool corals.

A crucial aspect of coral health and growth is their symbiotic relationship with zooxanthellae, microscopic algae. These algae live within the coral tissues and provide essential nutrients through photosynthesis, while the corals provide a protective environment for the zooxanthellae to thrive.

Understanding the relationship between polyps and zooxanthellae is vital for maintaining good water quality, light, and other essential factors contributing to healthy coral growth in a reef aquarium.

Aquarium Setup

When planning an aquarium setup for keeping corals, several basic requirements must be considered. These include the appropriate size of the tank, optimal water parameters, and the correct water flow and movement. This section will discuss these factors in detail to give you a better understanding of how to create the perfect environment for your corals.

Reef Tank Requirements

An essential part of keeping corals is setting up a well-balanced reef tank. A reef tank is a specific type of marine aquarium that aims to replicate the natural habitat of corals and other reef-dwelling organisms. In general, reef tanks require stable water parameters, proper lighting, and adequate water movement to promote the health and growth of the corals.

Size and Water Parameters

The size of the tank plays a significant role in maintaining stable water parameters. A larger volume of water offers a more significant buffering capacity, making it easier to maintain the necessary chemical balance for coral health. The following are some recommended water parameters for keeping corals in an aquarium:

  • Calcium: 400 to 450 ppm
  • Magnesium: 1200 to 1400 ppm
  • Alkalinity: about 2.1 to 2.5 meq/L
  • Specific gravity (salinity): 1.023 to 1.025
  • Temperature: 76 to 82 degrees Fahrenheit
  • Ammonia, nitrite, nitrate, and phosphate: 0 ppm

These parameters can be achieved through regular water changes, using high-quality salt mixes, and employing proper filtration systems, such as mechanical, chemical, and biological filtration methods.

Water Flow and Movement

Another crucial aspect of coral care is adequate water flow and movement within the aquarium. Corals thrive in environments with appropriate water currents, as they help deliver nutrients, remove waste, and provide oxygen. The use of powerheads and wavemakers can assist in creating a suitable water movement within the tank.

Each coral species might have specific preferences regarding flow and positioning in the tank. Therefore, it is essential to research the water flow requirements of the corals in your aquarium to ensure they receive the most suitable conditions for their growth and well-being.

Lighting and Temperature

When it comes to keeping corals in an aquarium, proper lighting and temperature play a vital role in ensuring their health and growth. Different coral species have varying light intensity, spectrum, and duration requirements. One common parameter to measure light intensity is Photosynthetically Active Radiation (PAR), and a good starting point is between 150 to 250 PAR.

Choosing the right light fixture for the aquarium is essential, considering the maximum PAR at specific depths. The color temperature of the light is measured in Kelvin (K), with most fish tanks typically ranging between 5,000 to 20,000 Kelvin. A higher Kelvin rating is suitable for deeper natural habitats, while a lower Kelvin rating is appropriate for shallow freshwater aquariums or reefs.

Short/Small Polyped Stony (SPS) corals are susceptible to lighting, requiring dynamic light sources for optimal growth. The advent of aquarium-related technology has made it possible to provide suitable lighting for such corals in a controlled environment.

Apart from lighting, maintaining the right temperature is crucial for coral health. The recommended temperature range for keeping corals in an aquarium is between 76 to 82 degrees Fahrenheit. To achieve this, an aquarium heater and a thermostat are essential equipment to monitor and adjust the temperature as needed.

Water Quality and Testing

Maintaining optimal water quality is essential for keeping corals healthy in an aquarium. Regularly testing various water parameters, such as pH, alkalinity, calcium, magnesium, ammonia, nitrite, nitrate, and phosphate, is crucial in ensuring a suitable environment for corals to thrive.

Handling Ammonia, Nitrite, Nitrate, and Phosphate

Ammonia, nitrite, and nitrate are byproducts of the nitrogen cycle in an aquarium, and excessive levels can cause stress and harm to corals. Monitoring these levels and maintaining ammonia at 0 ppm, nitrite at or near 0 ppm, and nitrate below 10 ppm for a healthy coral environment is essential. Keeping toxins under control is vital for the success of coral aquariums.

Phosphate levels in the aquarium should also be kept under control as high levels can cause algae blooms and negatively impact coral health. Aim for a phosphate level of 0.03 ppm or lower.

Balancing pH, Alkalinity, Calcium, and Magnesium

A stable pH is essential in a coral aquarium. Aim for a pH range between 8.1 and 8.4, ensuring the pH does not experience rapid swings. Regularly testing the pH and making minor adjustments to maintain the desired range is important for the overall health of the corals.

Alkalinity, calcium, and magnesium are essential water parameters for coral growth and health. Optimal levels to maintain in the coral aquarium are:

  • Alkalinity: 3.2-4.5 meq/L
  • Calcium: 380-450 ppm
  • Magnesium: 1250-1350 ppm

Monitoring and maintaining these parameters at the appropriate levels will create a suitable environment for the corals to thrive in.

Nutrition and Feeding

Proper nutrition and feeding are crucial for the growth and health of corals in an aquarium. Corals derive sustenance from various sources, including plankton, phytoplankton, and indirect absorption of dissolved organic compounds from the water.

Corals primarily feed on zooplankton and phytoplankton, microscopic organisms suspended in the water column. Providing a diverse and nutritionally balanced diet for corals is essential. Many commercial coral foods offer high protein content, bio-available amino acids, and essential omega-3 and -6 fatty acids for optimal coral health.

Two standard feeding methods for corals include target feeding and broadcast feeding. Target feeding involves directly feeding individual coral polyps with a pipette or turkey baster, while broadcast feeding involves mixing coral food with water and distributing it throughout the aquarium. Proper water flow is essential in facilitating feeding, as many corals require medium to strong currents to flush their surfaces of excess food particles.

Maintaining appropriate water parameters in the aquarium is vital for coral health. Some essential parameters include:

  • Calcium: 400 to 450 ppm
  • Magnesium: 1200 to 1400 ppm
  • Alkalinity: 2.1 to 2.5 meq/L
  • Specific gravity of natural seawater: 1.023 to 1.025
  • Temperature: 76 to 82 degrees Fahrenheit
  • Ammonia, nitrite, nitrate, and phosphate: 0 ppm

Regular monitoring and adjusting of these water parameters ensure proper coral nutrition and growth within the aquarium.

Supplements and Trace Elements

Corals in an aquarium require a proper balance of supplements and trace elements to ensure their growth and overall health. The primary supplements to consider are calcium, alkalinity, and magnesium, as these are the significant elements consumed by corals to grow their skeletons and support metabolic processes.

Calcium levels should ideally be maintained between 400 and 450 ppm, contributing to the rigidity of the coral skeletons. Magnesium levels should be maintained between 1200 and 1400 ppm, as it helps maintain proper calcium levels and supports various metabolic processes. Alkalinity is an essential parameter that helps maintain the balance of calcium carbonate precipitation and dissolution, and it should be kept around 2.1 to 2.5 meq/L.

In addition to the primary supplements, trace minerals and elements play a crucial role in the overall health of corals. These include factors such as:

  • Strontium
  • Iodine
  • Carbon
  • Bacterio (beneficial bacteria)

These trace elements should be provided in the right concentrations as they are essential for corals to perform chemical reactions, process food, grow, and reproduce. Regular testing and monitoring of water parameters, along with appropriate dosing, ensure that the corals receive the required supplements and trace elements to thrive in an aquarium environment.

Coral Compatibility and Placement

When keeping corals in an aquarium, it is essential to consider compatibility and proper placement. Maintaining a harmonious environment is crucial to ensure the health and growth of your corals.

Mixing Different Coral Types

There are various types of corals, and each has its unique requirements. When mixing different corals, you must consider light levels, water flow, and aggression between coral species. Some corals may release chemicals to deter other species, creating an unhealthy environment. Therefore, it is essential to research individual coral needs and adjust the aquarium environment accordingly. (World Wide Corals)

Various Colourful corals in an aquarium
Various Colourful Corals

Quarantine, Dips, and Acclimation

Before introducing new corals to your aquarium, it is imperative to quarantine them to avoid bringing unwanted pests, parasites, or diseases into the main tank. Typically, quarantine periods last for two to four weeks. Dips can also be used to remove pests and help sanitize corals. Be sure to don eye goggles and gloves for protection during this process.

Acclimation is another critical step when introducing new corals. Ensure that they gradually adjust to the water parameters such as temperature, salinity, and pH. This process may take a few hours, but it helps prevent shock or stress to the corals.

Fragging Corals

Fragging is propagating corals by cutting and attaching them to new substrates. This allows for increased growth and can help alleviate compatibility issues between coral species. Be cautious when handling corals, as some can be toxic or cause irritation. Wear gloves, eye protection, and use designated tools during the whole process.

Proper placement and arrangement of coral frags are also essential in maintaining balance within the tank. Corals need adequate space to grow and prevent aggressions that may arise when competing for resources or territory.

Maintaining a Healthy Coral Environment

Providing the right conditions for coral growth and thriving in an aquarium involves various factors, including water quality, water flow, lighting, and stability. Addressing these key elements helps create a suitable environment that mimics the natural seawater (NSW) and promotes the health of corals.

One essential factor is maintaining optimal water quality. This involves keeping a suitable temperature, pH, and salinity level. For example, most hard corals prefer water temperatures between 73°F and 84°F (23°C and 29°C) and can tolerate temperatures as low as 68°F (20°C) and as high as 89°F (32°C). In addition, monitoring the levels of substances like calcium, magnesium, and bicarbonate ensures corals receive the necessary nutrients for growth. For instance, maintaining a bicarbonate level of 8-12 dKH supports coral growth.

Water flow is also crucial in a coral tank. Corals require medium to strong currents to flush their surfaces of excess food particles and to ensure they absorb dissolved organic compounds from the water. Appropriate water flow also prevents the buildup of sediment on coral surfaces, imitating the natural wave action found in the ocean.

Another important environmental factor is providing adequate lighting. As photosynthetic organisms, corals rely on sufficient light for energy and growth. Therefore, ensuring the proper lighting conditions, and adjusting them based on coral species or requirements, promotes a balanced and healthy coral environment.

Lastly, stability is critical for coral health. Fluctuations in water quality, temperature, and other parameters can cause stress for corals and, in some cases, lead to coral bleaching. Monitoring the tank conditions closely and making consistent adjustments when needed helps maintain stability and support coral well-being.


To successfully keep corals in an aquarium, it is essential to understand and provide for their basic needs. These include proper lighting, water movement, suitable alkalinity, and appropriate temperature and salinity levels.

As a general rule, hard corals require more light than soft corals, with optimal conditions including alkalinity levels between 3.2-4.5 meq/L, temperatures ranging from 80-84°F, and salinity levels of 1.025 to 1.027, which is the specific gravity of natural seawater.

A key aspect of coral care is understanding their feeding requirements, as some corals have specific dietary needs that may be challenging to replicate in an aquarium setting. On the other hand, many corals can adapt well and thrive in a well-maintained tank.

Furthermore, maintaining proper water quality is crucial, as the correct concentrations of trace minerals and elements are necessary for corals to process food, reproduce, and thrive. By closely mimicking the conditions found in natural seawater and monitoring the health of the corals, a successful and thriving coral reef aquarium can be established and maintained.