Reefkeeping Glossary

Reefkeeping is an engaging and intricate hobby that demands a thorough understanding of a wide array of terms and concepts. As you embark on this journey, familiarizing yourself with the glossary of reefkeeping is crucial. It will not only enhance your communication with other enthusiasts but also improve your comprehension of the literature and resources available in the community.

Navigating through the various technical aspects becomes simpler when you grasp the terminology. From understanding the biological processes like nitrogen cycling to technical equipment such as protein skimmers, knowledge of these terms will become the bedrock of your reefkeeping endeavors.

Immersing yourself in this pastime involves more than just maintaining an aquarium; it is about nurturing a balanced and thriving ecosystem. Recognizing the subtle differences between terms such as “live rock” and “base rock” or “quarantine” and “hospital tanks” will provide you the insight to make informed decisions and troubleshoot issues effectively as you cultivate your own slice of the ocean.

Reef Aquarium Basics

In reefkeeping, understanding the fundamentals is crucial to maintaining a thriving aquatic environment. Key components include selecting the right type of aquarium, maintaining water chemistry, providing appropriate lighting, and choosing effective filtration methods.

Aquarium Types

You can choose between several types of aquariums for reefkeeping. The main types are:

  • Fish Only (FO): Housing only fish, without live corals or significant invertebrates.
  • Fish Only with Live Rock (FOWLR): Includes live rock which hosts beneficial bacteria, improving biological filtration.
  • Reef Aquarium: A complete ecosystem with live corals, fish, and invertebrates that mimics a natural coral reef habitat.

Water Chemistry

Water quality is essential for a healthy reef aquarium. Key parameters to monitor are:

  • Ammonia and Nitrites: Should always be at 0 ppm (parts per million) to prevent toxicity.
  • Nitrates: Ideally, kept low but can be tolerated up to 20 ppm depending on the system.
  • pH Level: A stable pH between 8.1 and 8.4 is necessary.
  • Salinity: Typically maintained at 1.023 to 1.025 specific gravity.

Lighting Requirements

Effective lighting supports coral growth through photosynthesis. Your lighting should consider:

  • Intensity and Spectrum: Mimic natural light conditions of a coral reef, with sufficient intensity for deep tanks.
  • Duration: Typically, 8-12 hours of light per day to simulate natural daylight cycles.

Filtration Methods

Filtration is what keeps your water clean and your inhabitants healthy. Your system should include:

  • Mechanical Filtration: Removes particulate matter from the water.
  • Chemical Filtration: Targets dissolved wastes, commonly with activated carbon or phosphate removers.
  • Biological Filtration: Relies on beneficial bacteria to convert toxic ammonia and nitrites into less harmful nitrates.

Livestock in Reefkeeping

Selecting and caring for your aquarium’s inhabitants is crucial. Your choices have significant impact on the ecosystem’s balance and health.

Coral Classification

Coral reefs are the backbone of any marine aquarium. You have two primary categories: hard corals (Scleractinia), which are the architects of coral reefs due to their calcium carbonate skeletons, and soft corals (Alcyonacea), which are flexible organisms without rigid skeletons. Hard corals are further divided into LPS (Large Polyp Stony) and SPS (Small Polyp Stony), with LPS being more tolerant to varying conditions and SPS requiring more precise care.

Fish Selection

Choosing fish for your reef tank demands consideration of compatibility, size, and behavior. Fish should be chosen based on their ability to coexist peacefully with corals and invertebrates. It’s essential to avoid species that are prone to nip at corals or disturb the substrate significantly. Prioritize species adapted to the size constraints of your tank and your skill level — for instance, smaller, peaceful fish like clownfish or dottybacks for beginners.

Invertebrate Care

Invertebrates, including crustaceans, mollusks, and echinoderms, play critical roles in your reef ecosystem. When caring for invertebrates, pay close attention to their specific dietary needs and compatibility with other tank inhabitants. For example, shrimp often help keep the tank clean by consuming detritus, while starfish may prey on coral or become prey themselves if not adequately accounted for within the tank’s hierarchy.

Reefkeeping Equipment

Selecting the right equipment is crucial to the success of your reef aquarium. Each piece plays a distinct role in creating a stable environment that mimics the natural habitat of the marine life you are looking to nurture.

Protein Skimmers

Protein skimmers are essential for removing organic compounds from aquarium water before they break down into nitrogenous waste. You typically install them in the sump and they work by creating tiny bubbles that organic materials adhere to, which are then collected in a collection cup for easy removal.

Aquarium Heaters and Chillers

Maintaining the appropriate temperature in your reef tank is critical. Aquarium heaters ensure your water stays warm enough, particularly in colder climates. Conversely, chillers might be necessary to prevent overheating in warmer environments or when high-intensity lighting systems are used.

Wave Makers and Powerheads

Circulation is vital in a reef aquarium, and wave makers and powerheads provide the water movement necessary for the well-being of your aquatic organisms. These devices help simulate natural water currents, contributing to the health of corals and facilitating the distribution of nutrients and gases throughout the tank.

Lighting Systems

Proper lighting not only enhances the visual appeal of your tank but is also fundamental for the growth and health of photosynthetic organisms like corals. LED lighting systems are popular due to their longevity, energy efficiency, and spectrum versatility. They must be chosen based on your specific tank inhabitants and their needs.

Water Quality Management

In reefkeeping, maintaining optimal water quality is crucial for the health of your reef. You’ll need to regularly manage nutrient levels, salinity, pH, and understand the nitrogen cycle to ensure a thriving ecosystem.

Nutrient Control

Nutrient control is vital to prevent algae blooms and keep your reef inhabitants healthy. You must regularly test and manage levels of nitrates and phosphates, which are common nutrients in the aquarium.

  • Nitrates (NO3): Keep below 10 ppm (parts per million).
  • Phosphates (PO4): Aim to maintain at or below 0.03 ppm.

Salinity and Specific Gravity

For coral and marine life to flourish, salinity and specific gravity need close monitoring. Salinity should be:

  • Between 1.023 and 1.025 for most reef tanks.

Measuring specific gravity will tell you the salt content of the water. Ensure it stays within the range of:

  • 1.023 – 1.026 at 77°F (25°C).

pH and Alkalinity

pH and alkalinity are basic indicators of your water’s chemistry. They affect the biological functions of your aquarium’s inhabitants. Your target pH range should be:

  • 8.1 – 8.4 for optimal coral growth and health.

Alkalinity, measured in dKH, helps stabilize pH. Strive for:

  • 8-12 dKH to support coral calcification and buffer against pH swings.

Nitrogen Cycle

Understanding the nitrogen cycle is essential to converting harmful waste products into safer compounds. The cycle involves:

  • Ammonia (NH3): Introduced through waste, should be quickly converted.
  • Nitrite (NO2): An intermediate toxic compound, should be undetectable.
  • Nitrate (NO3): The final nontoxic form, but should be kept in check.

Frequent testing for ammonia and nitrites is critical, as these should always be near zero in a well-established aquarium.

Aquascaping in Reefkeeping

Aquascaping is the thoughtful arrangement of rocks, corals, and substrate in a reef tank to create an aesthetically pleasing underwater landscape. This foundational aspect of reefkeeping not only serves an ornamental purpose but also supports the health and growth patterns of the marine life in the aquarium.

Rock Selection

When selecting rocks for your reef tank, consider both the biological function and visual appeal. Live rock is preferred for its beneficial bacteria, which aid in the nitrogen cycle. Opt for rocks with varied shapes and sizes to create a natural-looking reef structure. Ensure the rocks are stable and do not have sharp edges that could harm the tank inhabitants.

Coral Placement

Your coral placement decisions influence the look of your aquarium and the well-being of the corals. Place corals strategically, leaving space between them to accommodate future growth and to ensure adequate water flow. High-light corals should be toward the top of the aquascape, while low-light species can be positioned further down.

Substrate Choices

The substrate forms the bed of the aquarium and affects both aesthetics and the biological function of the tank. Choices range from fine sand to larger crushed coral. Fine sand provides a more natural look but can easily be stirred up, which might irritate some corals or inhabitants. Coarser substrates allow for better water flow through the bottom layers and can help reduce detritus buildup.

Feeding and Nutrition

Proper feeding and nutrition are essential in reefkeeping to maintain the health and vibrancy of your reef tank inhabitants. This section delves into specific techniques and products to ensure your coral and fish thrive.

Coral Feeding Techniques

Corals can obtain nutrients through photosynthesis performed by their symbiotic algae, but targeted feeding will provide them with the additional energy they need. Use a pipette or turkey baster to directly feed particulate foods or liquid suspensions to your corals. Always ensure water flow is low during feeding to prevent food from being swept away.

Fish Diets

Your fish require a balanced diet tailored to their species-specific needs, often a combination of dry and frozen foods. Omnivores can be offered a mix of plant and meat-based foods, while carnivores should have a protein-rich diet. Herbivores will benefit from algae-based diets. It’s critical to provide them with the proper size of food particles to facilitate easy consumption and digestion.

Supplements and Additives

To maintain optimal water chemistry and health of your reef tank, consider using supplements and additives like calcium, magnesium, and alkalinity buffers. These additives should be dosed carefully according to the specific demands of your reef tank, which can be determined by regular water testing. It’s also advisable to add trace elements and vitamins to support overall growth and vitality of your reef tank inhabitants.

Reef Tank Maintenance

Maintaining your reef tank is essential for the health of your marine inhabitants and the overall aesthetic appeal of your aquarium. Effective maintenance includes regular water changes, diligent cleaning practices, and proactive pest control.

Regular Water Changes


  • Weekly to bi-weekly changes are standard.
  • Volumes typically range from 10% to 25% of your tank’s total water capacity.


  • Remove excess nutrients and waste.
  • Replenish essential minerals and trace elements.

Cleaning Practices

Algae Management:

  • Use a scraper or magnetic cleaner to remove algae from the glass.
  • Regularly clean the substrate and live rock to prevent detritus build-up.

Equipment Maintenance:

  • Clean pumps, skimmers, and filters monthly to ensure optimal operation.
  • Replace filter media according to the manufacturer’s recommendations.

Pest Control


  • Regularly inspect coral and rockwork for signs of pests.
  • Pests can include aiptasia, bristle worms, and various parasites.

Management Strategies:

  • Use natural predators like certain fish or shrimps.
  • Manual removal or commercial remedies may be necessary for persistent issues.

Common Issues and Troubleshooting

In reefkeeping, you will encounter several challenges that need swift action to maintain a healthy aquarium. This section focuses on effectively identifying and resolving the most common issues: Algae Outbreaks, Disease Management, and Equipment Failure.

Algae Outbreaks

Algae outbreaks are a frequent concern in reef tanks and may indicate nutrient imbalances. To manage algae outbreaks, regularly test your water for nitrate and phosphate levels and consider these steps:

  • Limit Nutrients: Reduce feeding and improve filtration to lower nitrate and phosphate levels.
  • Increase Water Flow: Algae struggle in high flow, so increasing circulation can help prevent its growth.
  • Manual Removal: Remove visible algae by hand or with tools, being careful not to spread spores.

Disease Management

Dealing with disease involves keen observation and quick intervention. When you suspect an illness, such as the protozoan Cryptocaryon irritans (marine ick), take the following actions:

  • Quarantine: Move affected fish to a separate tank to prevent the spread to other inhabitants.
  • Medication: After identifying the specific disease, administer the appropriate medication according to the instructions.
  • Water Quality: Ensure optimal water conditions in the main tank to support the immune systems of the remaining fish.

Equipment Failure

Your tank’s ecosystem relies on functioning equipment. If you face an equipment failure, handle it with urgency:

  • Regular Checks: Periodically inspect and perform maintenance on equipment to pre-empt failures.
  • Emergency Kit: Keep a backup of essential items like heaters, pumps, and powerheads.
  • Proactive Replacement: Replace parts like gaskets and bulbs regularly to avoid sudden failures.

Advanced Reefkeeping Concepts

Advanced reefkeeping is about mastering the sophisticated aspects of managing a thriving marine ecosystem. It includes implementing automation for precision control, mastering propagation techniques, and adopting intricate ecosystem methods.

Reef Tank Automation

You can elevate the stability and performance of your reef tank through automation. Essential parameters like temperaturepHsalinity, and nutrient levels can be regulated using advanced systems. These typically involve programmable logic controllers (PLCs) or dedicated reefkeeping computers which allow for real-time monitoring and adjustment.

Propagation and Fragging

The practice of propagation, particularly through fragging, is a cornerstone of advanced reefkeeping. This process involves delicately cutting (fragging) corals or other invertebrates to create new, independent organisms. Proper fragging requires precise tools and methods to ensure successful growth and minimal stress on the parent and offspring.

Ecosystem Methods

Advanced reefkeepers often employ sophisticated ecosystem methods to maintain ecological balance. One such method is the Berlin Method, where live rock and protein skimming form the backbone of the filtration system. Additionally, aquariums may incorporate systems like algae turf scrubbers to naturally control nutrient levels through controlled algae growth that’s harvested periodically.