How to Create a Self-Sustaining Aquarium

If you could alter a single aspect of the aquarium hobby, what would it be? One common response might revolve around the necessity of performing regular water changes. While some individuals find tank maintenance therapeutic, others perceive it as a cumbersome task, especially those who manage multiple planted fish tanks. The need to drain and refill numerous aquariums on a weekly basis can consume more time than desired. So, what if there was a way to minimize or even eliminate the frequency of water changes altogether? In this blog post, we will delve into this topic and explore potential solutions that could revolutionize aquarium maintenance.

Understanding How Aquariums Work

Before we dive into the “how”, we need to first understand some principles of aquatic life. 

Why do we need to do water changes?

One of the fundamental concepts to grasp in the aquarium hobby is the nitrogen cycle. To simplify it, waste produced by fish and other organic matter, such as decaying plants or uneaten food, releases ammonia into the water. Ammonia is highly toxic and can be lethal to the aquarium inhabitants. However, there are specific bacteria, often referred to as "beneficial bacteria," that reside on or within the filter media, substrate, and various surfaces in the aquarium. These bacteria play a crucial role in converting ammonia into nitrites and, subsequently, into nitrates.

Nitrates are relatively tolerable to fish and shrimp when present in low concentrations. However, if nitrates accumulate to high levels, it can induce stress and, in severe cases, lead to the death of the aquatic organisms. This is why regular water changes are performed—to reduce the buildup of nitrates in the aquarium. For instance, if the nitrate level in the aquarium reaches 40 ppm, a 50% water change can be conducted to lower it to 20 ppm. By doing so, you are replacing half of the "contaminated" water with clean water, helping to maintain a healthier environment for your aquatic inhabitants.

How does water stay tolerable in nature?

There’s no one performing water changes on large bodies of water like oceans, lakes, and rivers, yet fish are still able to live in them. How can this be? For the most part, oceans have such a vast amount of water that the nitrate levels are probably insignificant. Meanwhile, freshwater lakes and rivers usually have plants growing in or on the edges of the land surrounding them. Nitrates are one of the nutrients that plants need to grow, so they uptake it through their roots and out of these bodies of water, thereby cleaning the water. There’s also a denitrification process that can happen in these natural sources for aquatic life that we will go more into later. 

Creating an Ecosystem

Now that we have gained an understanding of how both aquariums and natural bodies of water maintain cleanliness for fish to thrive, we can embark on the journey of creating self-sustainable setups within our fish tanks. The key to achieving this is to establish a harmonious ecosystem within the aquarium. Essentially, the aim of a self-sustainable aquarium is to mimic the natural processes and dynamics found in nature within the confined space of our tanks.

Plants: Our Biggest Helpers

The cornerstone of a self-sustainable setup is the abundance of plants. In such a system, a significant number of plants is essential as they act as natural filters. As previously explained, plants have the remarkable ability to absorb nutrients from their surroundings, including harmful compounds such as ammonia and nitrates that can pose a threat to fish and other aquatic inhabitants. By having a generous quantity of plants in the aquarium, the reliance on water changes is significantly reduced as the plants undertake the task of purifying the water. Ideally, the tank layout should be densely populated with plants, particularly fast-growing varieties like stem plants or floating plants. Their rapid growth ensures a more efficient uptake of nutrients from the water column, contributing to a healthier and more balanced ecosystem.

An intriguing approach to consider is incorporating elements of a paludarium by allowing some plants to grow emersed, or partially above the water surface. Emersed growth typically promotes faster plant growth, which can further enhance the removal of nitrates from the aquarium. Most aquatic plants have the ability to adapt and thrive in emersed conditions.

To create this layout, you can construct the substrate in the back of the tank at a higher level, allowing the plants to emerge above the water surface. This approach not only increases the effectiveness of nitrate removal but also provides the opportunity to include non-aquatic plants, such as terrarium plants, which adds diversity to the ecosystem.

While we recognize that a heavily planted tank is desirable, it's crucial to provide the plants with the optimal conditions for growth. Key requirements for plant growth include water, light, air, nutrients, and an appropriate temperature. In an aquarium setting, water is readily available, and plants utilize the dissolved oxygen and carbon dioxide in the water instead of relying on air. Maintaining a stable temperature within the suitable range for aquarium plants is typically achievable with the use of heaters. Therefore, the remaining factors to address are light and nutrients.

Tip: While water naturally contains some carbon dioxide (CO2), supplementing additional CO2 into the aquarium can accelerate plant growth, bringing us closer to achieving a truly self-sustainable setup!


Proper aquarium lighting is crucial for the health of your plants. It's recommended to keep your LED light on for approximately 6-8 hours per day to simulate natural sunlight. It's important to find the right balance, as lighting that is either too weak or too intense can harm certain plants or trigger excessive algae growth. Additionally, plants have specific wavelength preferences, known as the spectrum of lighting. Investing in an aquarium light specifically designed for growing aquatic plants can greatly benefit your setup. Ideally, choose a light that allows you to adjust the brightness, so you have the flexibility to dim it if needed.


In addition to ammonia and nitrates, plants require a range of nutrients to thrive in a planted aquarium. These nutrients can be provided through the substrate or fertilizers. It's important to ensure that the substrate is deep enough, allowing the plants to establish their roots at a depth of at least 1 1/2 - 2 inches. Fertilizers such as Plant Food All in One can also be added to the water column to provide additional nutrients for plants that may not be rooted in the substrate.

Once you have gathered all the necessary components, you can proceed to set up your aquarium!

Letting the Tank Establish

Once the tank is set up, it is important to allow the aquarium to run for a few weeks to ensure it undergoes a complete cycling process. This step requires patience, as adding fish too early can be harmful to both the livestock and the overall tank environment. The aquarium needs time to establish a stable nitrogen cycle, and the plants need time to root and acclimate before they can start thriving and growing.

During this initial period, it is necessary to perform frequent water changes to prevent the occurrence of severe algae blooms. As time progresses, the frequency of water changes can be gradually reduced. This phase is crucial for the establishment of beneficial bacteria and other microorganisms necessary for creating a self-sustaining ecosystem in your aquarium. Therefore, it is recommended to be patient and allow sufficient time for the ecosystem to develop before making any significant adjustments.

Aquarium Stocking

Once the aquarium has reached a suitable level of maturity, it is time to introduce fish and shrimp. However, it is important to err on the side of caution and maintain a low stocking density. The primary objective of a self-sustainable aquarium is to keep nitrate levels low, and overcrowding with fish can overwhelm the capacity of plants to absorb nitrates effectively. Begin with a small number of fish and monitor the aquarium's performance by regularly testing water parameters using a test kit. In setups with CO2 injection, a higher fish population can be accommodated compared to low-tech setups. If you are adding only shrimp, their waste production is typically lower than that of fish, so you may have more flexibility in terms of shrimp stocking.

Deep Sand Beds

In the pursuit of creating a self-sustainable aquarium, some aquarists explore the use of deep sand beds as a means of facilitating denitrification. Deep sand beds provide an environment for anaerobic bacteria to thrive, as the fine particles of sand restrict oxygen exchange. These bacteria convert nitrates into nitrogen gas, which is released into the atmosphere. However, it is important to note that establishing this process can be a lengthy endeavor, often taking several years. While the concept of eliminating the need for water changes may seem like a dream for many aquarium enthusiasts, it is essential to approach such methods with patience and careful consideration.

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