Starting up my freshwater aquarium

1. Choosing the right equipment

The choice of equipment is a fundamental step in ensuring the stability and longevity of your aquarium. First and foremost, it is important to define the fish you wish to keep, as their needs directly influence the volume, shape, temperature, filtration, type of substrate, and overall layout. Some species require a lot of space, others live in groups, and a few demand very specific conditions.

To get started properly, it is recommended to choose a tank of at least 60 L: below this volume, water parameters fluctuate too quickly, making biological balance more difficult to maintain.

The larger the volume, the easier the aquarium is to maintain, as chemical and thermal variations are less abrupt.

Essential equipment

Filtration

The filter must be powerful enough to circulate between 2 and 3 times the total volume of the aquarium per hour. This allows:

• Good water circulation,

• Effective removal of waste,

• Optimal bacterial colonization

Heater

For tropical fish, choose a heater providing around 2 watts per liter of water to maintain a stable and uniform temperature.

For cold-water fish, a heater is not necessary.

Lighting

LED lighting suitable for live plants is recommended to support their growth and ensure a natural balance.

Substrate

The substrate is an essential element for plants and for the development of beneficial bacteria.

• It is recommended to use a substrate specifically designed for plants (nutrient soil or technical substrate), which promotes rooting and plant growth.

• If this nutrient soil is covered with decorative gravel, adding a layer separator is useful to prevent the materials from mixing and to make maintenance easier.

• Plan for approximately 4 cm of gravel above the nutrient soil: this thickness provides excellent bacterial support and stabilizes plant roots.

  
  

Aquarium and stand

A solid and perfectly stable stand is essential to support the total weight of the setup.

2. Preparing the water and understanding its parameters

Aquarium water must meet specific requirements to ensure fish health and the proper functioning of the ecosystem. Understanding these parameters helps avoid most problems encountered during startup.

Essential parameters

pH

pH indicates the acidity or alkalinity of the water. Each species has its own suitable pH range, so it is important to know the needs of the fish you plan to keep.

GH (Total hardness)

GH corresponds to the concentration of minerals such as calcium and magnesium. It directly influences the well-being of fish and invertebrates.

KH (Carbonate hardness)

KH stabilizes pH. A KH that is too low causes sudden pH fluctuations, which are dangerous for fish.

Temperature

Most tropical fish require water between 24 and 26 °C, but some need higher or lower temperatures. Adjusting the temperature to the chosen species is essential.

Water preparation

When you fill an aquarium with water for the first time, it is not yet intended to house fish. The main goal is therefore to prepare the water in a way that promotes proper plant establishment.

Choose water that is not too cold, so as not to shock young shoots. A water conditioner can be added to improve tap water quality. The heater will then adjust the temperature without any additional intervention.

3. Understanding the nitrogen cycle

When the aquarium is filled with water and all the equipment is running, an essential biological process begins in your aquarium: the nitrogen cycle.

This is the most important stage when starting an aquarium, as it directly determines the balance of your aquarium and therefore a healthy environment for your fish.

The principle of the nitrogen cycle

Waste produced in the aquarium (uneaten food, fish waste, dead leaves, etc.) generates ammonia (NH₃/NH₄⁺), a substance that is highly toxic to fish.

Two types of beneficial bacteria will then transform these compounds:

Ammonia → Nitrites

Nitrosomonas bacteria convert ammonia into nitrites (NO₂⁻), which are still toxic.

Nitrites → Nitrates

Nitrobacter bacteria then convert nitrites into nitrates (NO₃⁻), which are much less toxic but accumulate.

Nitrates must then be removed through:

• consumption by plants,

• regular water changes.

  
  

  

  
  

Duration Fletcher

The nitrogen cycle generally takes 4 to 6 weeks to stabilize. During this period, it is normal to observe a rise in nitrites, followed by a gradual decrease.

Your aquarium will be ready to welcome its first fish when:

✔ ammonia is at 0

✔ nitrites are at 0

✔ nitrates are present but under control

4. Why are plants important?

Introducing plants from the very beginning helps provide the aquarium with a more stable and more natural environment. They contribute to:

• Improve water quality by absorbing part of the nitrates produced by the nitrogen cycle.

• Limit the appearance of algae by occupying space and consuming available nutrients.

• Create refuge areas, which reassures fish once they are introduced.

• Quickly stabilize the tank thanks to their role in biological balance.

In an aquarium during the startup phase, plants are a real support: they help the system establish itself smoothly.

Conclusion

Starting an aquarium requires a few essential steps, but with suitable equipment, carefully chosen plants, and simple, regular maintenance, it quickly becomes a truly stable and living ecosystem.

By taking the time to let balance establish itself and by respecting the needs of your future fish, you create a sustainable, healthy, and enjoyable environment to observe every day.