Reef Tanks 101: Setting Up & Caring for a Reef Aquarium

What is a Reef Tank?

A reef tank, often called a reef aquarium, is more than just a container filled with water and marine life. It’s a meticulously crafted ecosystem that mirrors the breathtaking beauty and complexity of natural coral reefs found in our vast oceans. Imagine having a slice of the Great Barrier Reef or the mesmerising coral gardens of the Maldives right in your living room. That’s the magic a reef tank brings.

But why go to great lengths to replicate these natural reef environments? The answer lies in the delicate balance of life that coral reefs support. These ecosystems are not just about the vibrant corals; they also play home to many marine species, from the tiniest of plankton to the most colourful fish. By emulating the natural habitat as closely as possible, we ensure the health and longevity of each organism within the tank.

Moreover, recreating a natural reef environment is crucial for the well-being of the corals themselves. In their natural habitats, corals have adapted to specific conditions—be it water temperature, salinity, or light levels. Straying too far from these conditions in a home aquarium can stress or even harm the corals.

As we delve deeper into the intricacies of setting up and maintaining a reef aquarium, remember that this isn’t just about aesthetic appeal. It’s about respect, responsibility, and a passion for preserving a tiny fragment of our planet’s incredible marine biodiversity. Welcome to the world of reef tanks!

The Basics of Setting Up a Reef Tank

Tank Size & Type

When setting up a reef tank, one of the most crucial decisions you’ll make is choosing the tank’s size and type. While it might be tempting to start with a smaller tank due to budget or space constraints, there are undeniable benefits to opting for a larger tank, especially for beginners.

Stability is key in reef aquariums. A larger volume of water is less susceptible to rapid changes in parameters like temperature and salinity. This means that larger tanks often provide a more stable environment, which is vital for the health of your marine inhabitants.

Let’s break down the common tank types you might encounter:

  • Nano Reefs: These are compact tanks, typically holding 30 gallons of water or less. While they can be a beautiful addition to a small space, they require meticulous care and frequent water changes due to their size.
  • Standard Tanks: Often ranging from 40 to 200 gallons, these are the most common type of reef aquariums. They provide ample space for various marine life and are more forgiving of minor mistakes, making them ideal for both beginners and seasoned aquarists.

Equipment Essentials

Setting up a thriving reef aquarium goes beyond just the tank and water. Here’s a list of must-have equipment to ensure your aquatic environment thrives:

  • Lighting: Corals rely on light for photosynthesis, making lighting an essential aspect of any reef tank. LED lights with adjustable spectrums are popular choices, allowing you to mimic the natural light cycles of the ocean.
  • Protein Skimmers: These devices remove organic compounds before they break down, ensuring clean water and reducing the load on your filtration system.
  • Pumps: Water circulation is crucial in a reef tank to ensure even distribution of nutrients and prevent dead spots. Invest in a reliable water pump to keep the water moving and aerated.
  • Heaters: Maintaining a consistent temperature is essential for the well-being of your marine life. Aquarium heaters ensure your tank’s temperature remains stable, especially during colder months.

Substrate & Rock

Last but not least, the foundation of your reef tank – the substrate and rock.

  • Live Rock: This isn’t just any ordinary rock. Live rock is laden with beneficial bacteria and microorganisms that play a pivotal role in the tank’s biological filtration. They break down waste products and provide nooks and crannies for marine life to hide and thrive.
  • Sand: Often used as a substrate in reef tanks, live sand contains beneficial bacteria that aid in breaking down waste. Moreover, it provides a natural look to the tank and can be a substrate for various bottom-dwelling creatures.

Incorporating these elements into your tank is not just about aesthetics; it’s about creating a symbiotic environment that mirrors the intricate balance of the natural reefs. As you layer your substrate and position your live rocks, envision the thriving ecosystem they’ll soon support.

Lighting in a Reef Aquarium

The Importance of Lighting for Coral Photosynthesis

One of the most striking aspects of a reef aquarium is the vibrant colouration of its corals. But did you know that this beauty isn’t just for show? It plays a crucial role in the survival of the corals. Much like terrestrial plants, corals rely on light to photosynthesise. Within the tissues of corals reside microscopic algae called zooxanthellae. These algae harness light energy to convert carbon dioxide and water into glucose, providing essential nutrients to the corals.

But it’s not just about keeping the corals alive. Proper lighting also ensures that corals retain their brilliant colours. Insufficient or inappropriate lighting can cause corals to fade and lose their vibrancy, while the right spectrum can accentuate their most vivid hues.

Different Types of Lights and Their Pros and Cons

LEDs (Light Emitting Diodes)

  • Pros:
    • Energy-efficient and have a long lifespan.
    • It can be customised to emit various spectrums, allowing for tailored lighting to match specific coral needs.
    • Generates less heat than other lighting types, reducing the need for additional cooling equipment.
  • Cons:
    • Upfront costs can be higher than other types of lights.
    • Light dispersion might be narrower than other sources, requiring multiple units for larger tanks.

T5s (T5 High Output Fluorescent Lights)

  • Pros:
    • Offers a broad and even light dispersion, ideal for large tanks.
    • Available in a wide range of colours and intensities, making it easier to find the perfect light for your setup.
    • It is more affordable upfront compared to LEDs.
  • Cons:
    • Less energy-efficient than LEDs, leading to higher long-term costs.
    • Bulbs must be replaced more frequently than LEDs, roughly every 9-12 months.
    • Generates more heat, potentially requiring cooling equipment.

Halides (Metal Halide Lights)

  • Pros:
    • Produces an intense light that can penetrate deeper tanks.
    • It offers a shimmering effect that mimics natural sunlight in the ocean, creating a visually stunning display.
  • Cons:
    • Consumes more energy than both LEDs and T5s.
    • Generates significant heat, often necessitating chillers or fans.
    • Bulbs need regular replacement, usually annually.

When selecting lighting for your reef aquarium, it’s vital to consider both the needs of your marine inhabitants and the specific requirements of your tank. Whether you opt for LEDs, T5s, or Halides, ensure you provide the right intensity and spectrum to create a thriving, radiant reef environment.

Water Quality and Parameters

Importance of Pristine Water Conditions

Just as we rely on clean air to breathe, the vibrant inhabitants of a reef aquarium rely on pristine water to thrive. The water quality in a reef tank can directly influence the health, colouration, and growth of the corals and marine life. Unlike larger oceans and seas, where water conditions are naturally stabilised over vast areas, the confined environment of an aquarium can be far more volatile. This makes it essential to ensure that the water in a reef tank remains as pure and stable as possible.

Parameters to Monitor

To achieve the best water quality, there are several key parameters that every reef hobbyist should monitor:

  • Salinity: This measures the concentration of salt in the water. The optimal salinity range for most reef tanks is between 1.023 and 1.025 specific gravity.
  • pH: Indicates the acidity or alkalinity of the water. A pH value between 8.1 and 8.4 is ideal for a reef aquarium.
  • Ammonia, Nitrites, and Nitrates: These are by-products of fish waste and decaying organic matter. While ammonia and nitrites should always be at zero, a small amount of nitrates can be tolerated.
  • Calcium: Essential for the growth of corals and other calcifying organisms. An ideal range is between 380 and 450 ppm.
  • Alkalinity: Helps buffer the water and maintain a stable pH. Aim for a dKH between 7 and 12.
  • Magnesium: Works in conjunction with calcium and alkalinity. Its optimal level is between 1250 and 1350 ppm.

Water Testing and Maintenance Routines

Regular testing is the key to understanding and maintaining the health of your reef tank. Here’s a general guide to help you:

  • Weekly Testing: Test for ammonia, nitrites, nitrates, and pH. These parameters can fluctuate rapidly and immediately impact the tank’s inhabitants.
  • Bi-weekly to Monthly Testing: Test for calcium, alkalinity, and magnesium. While these parameters stay relatively the same, they are essential for coral health and growth.
  • Routine Water Changes: Every 2-4 weeks, replace 10-20% of the tank’s water with fresh, saltwater mix. This helps dilute accumulating toxins and replenishes essential minerals.
  • Regular Equipment Maintenance: Clean and inspect equipment like pumps, protein skimmers, and heaters. Ensuring they function correctly will aid in maintaining stable water conditions.

The secret to a thriving reef aquarium lies in its water quality. By staying diligent with monitoring and maintenance, you create an environment where every organism can flourish. Remember, the beauty of a reef tank is not just in its appearance but also in the harmonious balance of its water parameters.

Filtration & Water Movement

The Three Types of Filtration

In the intricate world of reef tanks, maintaining clean and clear water is paramount. This is achieved through a combination of filtration methods, each serving its distinct purpose:

  • Mechanical Filtration: As the name suggests, this method mechanically removes particles from the water. Using media like foam pads, sponges, or filter socks, it captures debris, uneaten food, and detritus. This not only helps in keeping the water clear but also prevents these particles from decomposing in the tank, which could lead to poor water quality.
  • Chemical Filtration: Using media like activated carbon, chemipure, or resins, chemical filtration absorbs and removes various pollutants, discolourations, odours, and toxins from the water. It’s crucial to replace these media regularly to ensure their efficiency.
  • Biological Filtration: At its core, biological filtration relies on beneficial bacteria to break down harmful ammonia and nitrites produced from fish waste and uneaten food into less harmful nitrates. This is often achieved with live rock, ceramic rings, or bio-balls, which provide a surface for these bacteria to colonise.

Importance of Water Movement for Coral Health and Feeding

Water movement is essential in replicating the natural ocean environment where corals thrive. Proper water flow ensures:

  • Oxygenation: A constant flow helps exchange oxygen and carbon dioxide, essential for corals and fish.
  • Feeding: Many corals are filter feeders, capturing tiny food particles from the water. An adequate flow ensures these nutrients are delivered to them.
  • Waste Removal: A steady current prevents detritus from settling, carrying it to the filtration system.
  • Coral Health: Proper water movement prevents dead spots, which can lead to algae growth. It also ensures that the entire coral receives light, aiding in photosynthesis.

Different Types of Current Makers and Their Benefits

In the quest to achieve the perfect water flow, various devices can be employed:

  • Powerheads: Compact and versatile, powerheads are popular choices for many reef hobbyists. They produce a directed flow, which can be adjusted as needed.
  • Wave Makers: These devices create a more natural, wave-like motion in the tank. This undulating movement can be very beneficial for certain types of corals.
  • Gyre Generators: Offering a unique flow pattern, gyre generators move water in a circular motion, ensuring flow reaches even the farthest corners of the tank.
  • Return Pumps: Part of a sump system, these pumps return filtered water to the main tank, creating additional flow.

Both filtration and water movement play vital roles in maintaining the health and beauty of a reef aquarium. By understanding their importance and ensuring their proper implementation, you set the stage for a thriving underwater paradise.

Stocking a Reef Aquarium

Choosing the Right Corals

When diving into the colourful world of corals, there are many species to choose from, each with unique needs and aesthetics. Broadly, they can be categorised into two:

  • Hard Corals: These corals have a rigid exoskeleton made of calcium carbonate, providing a stony appearance. Examples include Brain Corals, Staghorn Corals, and Pillar Corals. They are generally more challenging to care for as they have specific lighting and water parameter requirements.
  • Soft Corals: Unlike their hard counterparts, soft corals lack a rigid skeletal structure. Species like Leather Corals, Zoanthids, and Mushroom Corals fall under this category. They are often recommended for beginners due to their adaptability and less stringent requirements.

Introducing Invertebrates

Invertebrates not only add diversity to your reef tank but also serve various functional purposes:

  • Shrimps: Cleaner shrimps, such as the Skunk Cleaner Shrimp, are beneficial as they eat parasites off fish. Meanwhile, Peppermint Shrimps are known to control pest anemone populations.
  • Crabs: Creatures like Hermit Crabs and Emerald Crabs are scavengers, helping to clean up detritus and uneaten food.
  • Snails: Snails, especially Turbo and Trochus Snails, are great algae grazers, helping control algae growth in the tank.

Picking Reef-Safe Fish

When selecting fish for your reef aquarium, ensuring they are reef-safe—that is, they won’t harm your corals or invertebrates—is crucial. Here’s a list of popular reef-safe fish and a brief on their care:

  • Clownfish: Perhaps the most iconic reef fish, Clownfish are hardy and come in various colour morphs. They often form symbiotic relationships with anemones.
  • Tangs: Surgeonfish, commonly known as Tangs, like the Yellow Tang or the Regal Blue Tang, are fantastic algae grazers. They do require larger tanks due to their active nature.
  • Blennies & Gobies: Small and full of personality, these bottom-dwellers are entertaining and functional. The Bicolor Blenny, for instance, helps control algae, while the Watchman Goby pairs with pistol shrimps, showcasing unique behaviours.
  • Royal Gramma: A colourful and peaceful fish, the Royal Gramma is a fantastic addition to most reef tanks. They prefer caves and overhangs to dart in and out of.
  • Wrasse: The Cleaner Wrasse is beneficial as it eats parasites off other fish. However, not all Wrasses are reef-safe, so it’s essential to research before adding them to your tank.

When stocking a reef aquarium, patience is key. Slowly introducing inhabitants, monitoring their health, and ensuring compatibility will lead to a vibrant, thriving ecosystem.

Maintenance & Upkeep

Maintaining a healthy reef aquarium is a continuous commitment. While it’s a rewarding experience to watch your marine ecosystem flourish, it’s essential to understand that the vitality of the aquarium inhabitants relies on regular upkeep. Here’s a guide to ensure your reef aquariums remains vibrant and thriving.

Regular Water Changes

The Importance: Water changes are the backbone of aquarium maintenance. Over time, toxins, waste, and other undesirable elements can accumulate in the tank water. Regular water changes help dilute these impurities, providing a cleaner environment for your tank’s inhabitants. Moreover, they replenish essential minerals and trace elements that corals and other marine life need to thrive.

How Often and How Much: Typically, for a reef aquarium, it’s recommended to change 10-20% of the tank water every two weeks. However, the frequency can vary based on the tank’s bioload and specific needs. It’s always a good idea to monitor water parameters to determine the optimal water change routine for your setup.

Cleaning and Maintaining Equipment

Why It’s Crucial: Equipment such as protein skimmers, pumps, and heaters play a pivotal role in maintaining the tank’s stability. Ensuring they are functioning optimally is crucial for the health of the ecosystem.

Routine Checks: Inspect equipment regularly for any signs of wear or malfunction. Clean protein skimmers to ensure they are working efficiently. Pumps and powerheads can get clogged with detritus or algae; ensure they are cleaned periodically. Heaters should be checked, especially during seasonal changes, to make sure they are maintaining the desired temperature.

Monitoring and Dosing Trace Elements

The Role of Trace Elements: Corals and other marine invertebrates require specific minerals and trace elements, like calcium, magnesium, and strontium, to grow and maintain their skeletal structures.

Monitoring: Regularly test the water for levels of these essential elements. Over time, as corals grow and use up these minerals, they need to be replenished.

Dosing: Based on the test results, you may need to dose your aquarium with specific trace elements. Commercially available additives can be used to restore the necessary levels. Always follow the manufacturer’s guidelines when dosing and avoid making drastic changes quickly. It’s always better to make gradual adjustments.

While reef aquariums can be demanding, with regular maintenance and a keen eye on the tank’s condition, it’s entirely possible to maintain a flourishing marine ecosystem that provides endless enjoyment and fascination.

Common Challenges & Solutions

Every hobby comes with its unique set of challenges, and reef keeping is no exception. As you venture deeper into the world of reef aquariums, you’ll likely encounter a few hiccups. However, understanding these challenges and their solutions can ensure your reef remains vibrant and healthy.

Coral Bleaching

What it is: Coral bleaching occurs when corals lose their vibrant colours, turning white. This happens when the symbiotic algae, known as zooxanthellae, which live inside the coral tissues, get expelled. This algae provides the coral with essential nutrients, and its loss can be detrimental.

Common Causes: Stress factors such as sudden changes in water temperature, poor water quality, or excessive light can lead to coral bleaching.


  • Regularly monitor water parameters and ensure they remain stable.
  • Gradually acclimate corals to new lighting conditions.
  • Implement cooling systems during hot periods to regulate temperature.

Algae Blooms

What it is: A sudden proliferation of algae in the tank, giving the water a cloudy or greenish appearance.

Common Causes: Excess nutrients, especially nitrates and phosphates, often fuel algae growth. Overfeeding or decaying organic matter can contribute to this.


  • Reduce feeding and ensure uneaten food is removed promptly.
  • Use a protein skimmer to remove organic waste.
  • Introduce algae-eating organisms like snails or hermit crabs.
  • Consider using specialised media or chemicals to reduce phosphates and nitrates.


What they are: Unwanted organisms, such as aptasia (a type of anemone), bristle worms, or certain types of crabs and snails, that can harm corals or disrupt the tank environment.


  • Be cautious when introducing new live rock or corals. Quarantine new additions to prevent pests from entering your main tank.
  • Use natural predators. For instance, peppermint shrimp are known to eat aptasia.
  • Manually remove larger pests using tweezers or similar tools.

Tips for Maintaining a Thriving Reef Ecosystem

  1. Stay Informed: The world of reef keeping is ever-evolving. Stay updated with the latest research and best practices.
  2. Observe Regularly: Spend time observing your tank daily. Early detection of problems can make solutions more effective.
  3. Be Patient: Avoid making hasty changes. Slow and steady often wins the race in reef keeping.
  4. Join a Community: Connect with fellow hobbyists through online forums or local clubs. Sharing experiences can provide valuable insights.

While challenges in reef keeping are inevitable, they are surmountable. With knowledge, patience, and some troubleshooting, you can ensure your reef aquarium remains a stunning spectacle for years.


The journey of setting up and maintaining a reef aquarium is akin to curating a masterpiece. Every element, from the shimmer of the fish to the vibrant hues of the corals, comes together to create a captivating, living work of art. Just as an artist painstakingly chooses each brushstroke, a reef hobbyist meticulously curates their aquatic environment. The result? A mesmerising underwater world that offers endless wonder and fascination.

However, as with any rewarding endeavour, maintaining a reef tank comes with challenges. From ensuring the perfect lighting to warding off potential pests, there’s always something to learn, tweak, or perfect. Yet, it’s these very challenges that make the successes all the more gratifying.

For those teetering on the edge of diving into this hobby, remember every reef keeper started with a dream and an empty tank. The magic lies in transforming that vision into a thriving underwater realm. While research is your compass, patience will be your constant companion. As with any pursuit, there might be hurdles, but the breathtaking beauty of a well-maintained reef tank makes every effort worth it.

So, to all aspiring aquarists, take that leap and immerse yourself in the enchanting world of reef aquariums. With diligence, passion, and a sprinkle of patience, you’ll find yourself captivated by the joys of creating and nurturing your very own slice of the ocean. Dive in, and let the wonders of the deep blue inspire and mesmerise you.

Additional Resources

Embarking on setting up and maintaining a reef aquarium is exciting and challenging. To ensure that you’re well-equipped and informed, it’s beneficial to tap into various resources. Whether you’re looking for in-depth knowledge, troubleshooting tips, or simply a community of like-minded enthusiasts, here are some top resources that can guide and assist you:


  1. “The Reef Aquarium” Series by Julian Sprung and Charles Delbeek: A three-volume series that provides a comprehensive overview of the science and art of maintaining a reef aquarium.
  2. “Aquarium Corals: Selection, Husbandry, and Natural History” by Eric H. Borneman: An essential guide to understanding, selecting, and caring for corals.


  1. Reef2Reef A bustling online community where reef hobbyists from beginners to experts converge to discuss, share, and learn.
  2. Reef Builders A website that covers the latest news, product reviews, and innovations in the reef aquarium industry.


  1. Nano-Reef Community Focused on nano reef tanks, this community is a treasure trove of information for those working with smaller aquariums.
  2. Reef Central One of the oldest and largest online forums dedicated to reef aquariums, where you can discuss almost every topic imaginable.

Other Resources

  1. Local Aquarium Clubs: Joining a local club or society can provide hands-on experiences, workshops, and the chance to connect with experienced hobbyists.
  2. YouTube Channels: Many experienced aquarists share their journey, tips, and tutorials on YouTube. Channels like “Bulk Reef Supply” and “Tidal Gardens” offer rich visual content.
  3. Aquarium Apps: Tools like “AquaPlanner” and “Reef Trace” can assist in tracking maintenance tasks, monitoring water parameters, and setting reminders.

Remember, while these resources offer much information, nothing beats personal experience. Engage with the community, experiment (responsibly) with your setups, and most importantly, enjoy every moment of the journey in this mesmerising underwater world.

Frequently Asked Questions (FAQs) about Reef Tanks

1. What is the ideal size for a beginner’s reef tank?

Answer: While there’s no strict rule, larger tanks (around 30-55 gallons) tend to be more forgiving as they provide greater stability in water parameters. However, nano reefs (under 30 gallons) are popular for those with limited space, though they might require closer monitoring.

2. How often should I perform water changes in a reef tank?

Answer: Typically, a 10-20% water change every two weeks is recommended for most reef aquariums. However, this can vary based on the tank’s size, bioload, and specific needs.

3. Are all fish safe for reef tanks?

Answer: No, not all fish are reef-safe. Some fish might nibble on or damage corals. It’s essential to research and choose fish known to be compatible with reef environments.

4. Why are my corals losing colour or turning white?

Answer: Coral bleaching, where corals lose their colour, can be due to various reasons such as poor water quality, incorrect lighting, or sudden changes in water parameters. Addressing the underlying issue and providing stable conditions can often help corals recover.

5. Can I add any type of sand to my reef tank?

Answer: It’s best to use live sand or aragonite-based sands designed for marine and reef aquariums. These sands support beneficial bacteria and maintain stable pH levels.

6. How do I deal with algae blooms in my reef tank?

Answer: Algae blooms can be due to excessive nutrients, inadequate water movement, or light imbalances. Regular maintenance, using clean source water, appropriate lighting durations, and introducing algae-eating invertebrates can help manage and prevent algae blooms.

7. Do I need to dose trace elements in my reef tank?

Answer: As corals grow, they consume certain trace elements. While regular water changes replenish many of these, some advanced reef aquariums with fast-growing corals might benefit from additional dosing. Regular testing and monitoring are essential.

8. What is the difference between hard and soft corals?

Answer: Hard corals have a rigid skeleton and are the primary reef builders, while soft corals lack a solid skeleton and have a more flexible structure. The care requirements and lighting needs can differ between the two.

9. Can I use tap water in my reef aquarium?

Answer: Tap water can contain chlorine, chloramines, and other impurities detrimental to a reef environment. It’s recommended to use RO/DI (Reverse Osmosis/Deionized) water for topping off and water changes.

10. How long should I run the lights in my reef tank?

Answer: Most reef tanks benefit from 8-12 hours of light per day, but this can vary based on the specific needs of the corals and algae in the tank. Using timers can help maintain a consistent light cycle.

Remember, every reef tank is unique, and while these FAQs provide general guidelines, always be prepared to adjust based on the specific needs and conditions of your aquarium.