Setting Up a Reef Aquarium: Budget, Equipment and Species for Beginners

Setting up a reef aquarium involves recreating a tropical coral reef ecosystem in a controlled environment. Although technically demanding, this type of project is accessible to beginners provided that it is carefully planned: establishing a suitable budget, choosing the right equipment and selecting hardy species that are biologically compatible with one another. Here are the key points to consider when starting a marine aquarium.

Planning the Initial Budget and Ongoing Costs

Before starting a marine aquarium project, it is important to anticipate the overall budget involved to avoid unexpected expenses later on. The budget should take into account both the initial purchase and setup costs and the ongoing running costs.

For the initial setup, a budget of between €10 and €15 per litre of water can be expected. This estimate includes the aquarium, stand, filtration system, lighting and the first invertebrates and fish. For a 200-litre aquarium, the initial cost therefore ranges from approximately €2,000 to €3,000. All-in-one aquariums with integrated filtration account for a significant proportion of this budget.

The main ongoing running costs include:

• Electricity consumption: intensive lighting, circulation pumps running continuously and constant heating at 25 °C represent a significant expense.
• Marine salt and reverse osmosis (RO) water: these are essential for carrying out regular water changes.
• Supplements required for coral growth: calcium, strontium, magnesium and trace elements.
• Filtration consumables: these include activated carbon, resins and replacement reagents used for water testing.
• Food for marine fish and invertebrates: pellets and frozen foods should be selected according to the dietary requirements of the different marine species.

Essential Equipment for Getting Started

Keeping corals and marine fish in an aquarium requires stable water conditions, which can only be maintained with suitable technical equipment.

Aquarium volume

For beginners, a volume of between 200 and 300 litres is recommended. Contrary to what might be expected, smaller aquariums of less than 80 litres are considerably more difficult to manage. A larger volume of water provides greater thermal and chemical stability. As a result, dosing errors or water evaporation have a more gradual impact, providing more time to intervene.

The protein skimmer

A protein skimmer injects microbubbles of air into a column of water to capture organic matter before it breaks down into toxic pollutants. The skimmer should be sized to handle approximately twice the actual volume of the aquarium.

Water circulation

Corals cannot move to capture food or remove accumulated sediment. Dynamic water circulation is therefore essential to recreate natural ocean currents. At least two circulation pumps should be installed to create turbulent, alternating water flow. The total flow rate should be approximately 20 to 30 times the aquarium volume per hour.

Lighting

Corals host symbiotic algae known as zooxanthellae, which require light for photosynthesis and contribute to the coral's nutrition. The lighting system must therefore provide an appropriate light spectrum.

The automatic top-off system

Aquarium water continuously evaporates as a result of heat and water movement, while the salt remains behind. To prevent salinity from rising to levels that could be lethal to marine animals, an automatic top-off (ATO) system automatically replaces evaporated water with pure reverse osmosis (RO) water stored in a dedicated reservoir. This equipment is therefore essential for maintaining the stability of the aquarium ecosystem.

Choosing the Rockwork and Establishing the Biological Cycle

The biological filtration of a reef aquarium relies on porous rock that also forms the aquarium's natural aquascape.

A marine aquarium can be set up using cultured live rock, wild live rock collected from the sea, or dry calcareous rock that needs to be seeded with bacteria. These porous rocks provide a vast surface area for billions of beneficial bacteria to colonise. These bacteria break down organic waste through the nitrogen cycle. For a 200-litre aquarium, approximately 10 to 15 kg of porous rock should be used.

Once the rockwork has been installed and the water prepared, with a salinity of between 33 and 35 g/L, the aquarium enters its maturation phase. This waiting period of 6 to 8 weeks is necessary to allow bacterial colonies to establish, pass through a spike in toxic nitrite levels and eventually stabilise. No marine fish or invertebrates should be introduced into the aquarium during this period.

Fish and Coral Species Suitable for Beginners

The first livestock introduced into the aquarium should consist of hardy species that can tolerate minor fluctuations in water parameters and are not aggressive, helping to ensure successful coexistence with other species introduced later.

Clean-up crew invertebrates

These marine organisms should be introduced only once the nitrogen cycle is fully established and nitrite levels have returned to zero. Clean-up crew invertebrates play an important biological role by consuming unwanted algae and sediment that has accumulated on the rockwork.

Snails help clean the glass and live rock, hermit crabs consume organic debris and leftover food that settles on the substrate, while shrimp help remove food residues and, depending on the species, may also contribute to removing parasites from fish.

Fish for beginners

Fish should be introduced gradually to allow the bacterial populations to adapt to the additional organic load. The clownfish (Amphiprion ocellaris) is one of the most common choices for beginners due to its hardiness, adaptability and ability to live as a stable pair.

Soft corals

For beginners, it is preferable to avoid hard corals and focus on soft corals, as they are generally much more tolerant of dissolved nutrients. Zoanthus are small colonial polyps that quickly form dense, colourful mats across flat areas of the rockwork. Mushroom corals of the genus Discosoma are particularly well suited to colonising shaded areas and less exposed parts of the aquarium.

Key Practices for Maintaining a Healthy Marine Aquarium

The long-term viability of a reef aquarium depends on consistent maintenance, particularly during the first few months.

One of the most important practices is to carry out regular water changes. Replacing 5% of the total water volume every week helps keep accumulated nitrates under control and replenishes trace elements consumed by corals.

Water parameters should initially be monitored on a weekly basis. Salinity should remain stable at 35 g/L at a temperature of 25 °C. An electronic refractometer provides accurate measurements. Nitrate tests should show low levels, ideally below 10 mg/L, to maintain suitable conditions for corals and limit the growth of unwanted filamentous algae.

Finally, marine fish and invertebrates should be fed in small daily portions. Fish should consume all the food within two minutes to prevent excess food from settling on the substrate and polluting the aquarium ecosystem.