What Is An Aquaponics Biofilter? - Go Green Aquaponics

What Is An Aquaponics Biofilter?

The idea behind aquaponics is that it is possible to imitate nature and create a perfect growing environment for fish and plants with the help of beneficial bacteria. However, maintaining a healthy and balanced aquaponics ecosystem can be challenging without the use of a biofilter. It is because a biofilter helps remove excess solid waste from the water and maintains good water quality for the plants, fish, and beneficial bacteria to thrive. This article will explore what aquaponics biofilters are, how they work, and why they are essential for the success of an aquaponics system.

What Is a Biofilter and Why Is It Important in Aquaponics?

A biofilter is an essential component of an aquaponics system that removes solid waste from the water and helps maintain a healthy environment for fish and bacteria. 

A biofilter is also a place for the beneficial bacteria to colonize and provide a large surface area for the bacteria to live and thrive. These beneficial bacteria convert ammonia, nitrites, and nitrates into nutrients for plants.

The process of converting fish waste into plant nutrients creates ammonia which is toxic to fish and plants. This is where the biofilter comes in, as it helps break down ammonia into plant nutrients. 

In aquaponics systems, a biofilter is a biological filter that contains colonies of beneficial bacteria that convert ammonia, nitrites, and nitrates into nutrients for the plants. The beneficial bacteria are also essential to the nitrogen cycle, which is a process that helps maintain a healthy balance in the system. 

Without a properly functioning biofilter, the ammonia levels and other harmful substances can build up quickly, which can lead to poor water quality and, eventually, the death of fish and plants. Moreover, a lack of biofiltration can lead to poor plant growth, reduced yields, and failure of the system. By using biofilters, aquaponics growers can ensure their system is a sustainable and environment-friendly farming method. 


Biofilters In Aquaponics

Benefits of Using Aquaponics Biofilter

  1. A biofilter provides more surface area for the beneficial bacteria to live and helps convert ammonia into nutrients for the plants. 

  2. A biofilter assists in the aeration and nitrification process in the Nutrient Film Technique (NFT)Raft (DWC), and Vertical Aquaponics System, where there is no grow bed for the beneficial bacteria to colonize.

  3. A biofilter helps improve the system's water quality by removing other solid waste, such as excess fish food

  4. It helps enhance plant growth.

  5. By using biofilters, the need for chemical fertilizers is reduced, which helps lower operating costs. 

  6. biofilter is easy to use and requires very little maintenance.

Important Factors to Consider In Using Aquaponics Biofilter

Before you decide to use biofilter in your aquaponics system, you must be aware of these considerations.

1. Remove The Solids First

Biofilters cannot remove large solid waste, so solids must be screened because this will possibly block the pipes. Once these solids accumulate in your biofilter, this will create areas known as aerobic zones that will attract harmful bacteria and reduce your biofilter's surface area. This will reduce your biofilter's efficiency, resulting in a high ammonia level, which is unsuitable for fish and plants. That is why it is essential that you add a standard filter that will remove the solid.

2. Bacteria Need Air

In an aquaponics system, the bacteria need air. So you have to ensure that your filter has enough air supply to ensure the bacteria are not deprived of air.

3. Fish Density

If you are running a low fish density, then you don't need a biofilter. Low quantities of fish will not produce enough waste to justify using a biofilter. The plant's roots will provide enough surface area for the bacteria to convert ammonia into nitrates.

How Biofilters in Aquaponics Work?

Biofiltration in aquaponics happens in three main steps. This process is for a typical aquaponics setup. The process or steps may vary depending on your biofilter design.

1. The air pump pumps the water out of the fish tank and into the biofilter.

2. Inside the biofilter, the water goes through the nitrification process. The beneficial bacteria help convert ammonia and nitrites into nitrates.

3. The water full of nutrients flows out of the biofilter and into the plants, where the plant roots absorb the nutrients while cleaning the water before it goes back into the fish tank.



Types of Biofilters Used in Aquaponics Systems

There are several aquaponics biofilters that you can use in your aquaponics system; these are:

1. Moving Bed Biofilter

This biofilter uses a bed of media that moves through aeration or water flow to provide surface area for the beneficial bacteria to thrive. This type of biofilter is often used in a floating raft system of aquaponics. 

2. Static Media Biofilter

This biofilter uses a bed of static media, such as gravel, to provide a surface area for the beneficial bacteria to grow. The filters are slid into a separate container positioned next to the fish tank before the plants, allowing the water to be filtered before reaching the plants. 

3. Drip Filter

This filter allows water to drop in from the top. The water passes through the filter box, full of gravel, oyster shells, or another similar bio medium with lots of surface area. This biofilter must also be positioned where the water is filtered before it reaches the plants. As the water moves through the filter, the ammonia is converted to nitrates before it is pumped back to the plants.

The type of biofilter used in an aquaponics system will depend on the specific needs of your system, the size of your system, and the available space for the filter.

Maintenance of Aquaponics Biofilters

Proper maintenance of your biofilter is essential in ensuring the proper function of your aquaponics system and in preventing any issues that can affect the health of the fish and plants. Here are some tips for maintaining a biofilter in your aquaponics system.

1. Regular Monitoring of Water Quality

Monitoring water quality is essential in ensuring the biofilter is functioning correctly. You can do this by regularly testing the water for ammonia, nitrites, and nitrates levels to determine if adjustments need to be made to the biofilter. This can be done by using water test kits or electronic monitoring devices.

2. Regular Cleaning of Biofilter Media

Cleaning the biofilter media regularly can prevent clogging and ensure the biofilter is functioning correctly at all times. Over time, solid waste particles and other debris can accumulate in the biofilter, reducing its surface area and preventing beneficial bacteria from growing. You can clean the biofilter media by rinsing it with clean water or soaking it in a solution of water and vinegar.

3. Maintaining the Correct pH Levels and Temperature

The biofilter bacteria require specific pH and temperature conditions to grow and function correctly. The ideal pH range for an aquaponics system is between 6.8 and 7.2, while the optimal temperature range is between 20 and 28°C (68-82°F). Regular monitoring of pH levels and temperature can help maintain optimal conditions for the bacteria in the biofilter.

4. Avoid Overfeeding Fish

Overfeeding fish can lead to an accumulation of uneaten food in the fish tank, which can clog the biofilter and lead to issues with water quality. Feeding fish small amounts of food a few times a day can help prevent overfeeding and ensure they get the nutrients they need without overloading the system.

4. Adding Beneficial Bacteria

If the biofilter is not functioning correctly or there is a sudden increase in fish or plant load, adding beneficial bacteria can help boost the system's performance. You can add beneficial bacteria in the form of commercial products.


Good biofiltration is a critical component of an aquaponics system because it is essential for the chemical stability of your system. That is why it is important to understand the role of a biofilter in aquaponics to know if your system needs a biofilter. Thank you for reading our article. If you have any comments, feel free to leave them below.


3 Responses



July 27, 2021


Wm David Wilhelm

Wm David Wilhelm

July 27, 2021

In addition to a Bio media filters for fish outlets, I am considering using a Bio media pre-filter for all returns from plant media beds for fine particulate accumulation and additional mineralization with airlift and higher O2 levels for fish. If it all works, as designed and will reduce the addition of nutrient top off and JAW (just add water) is the goal and best wishes to all. Hint, hint, Catfish for any Crayfish that get loose from the system floating mats, vertical racks primers for faster nutrient uptake crops and cleaner clearer water. Circularize your plant media beds for less stagnation and anaerobic activity, by spiralizing the water flow.

Daniel Schneekloth

Daniel Schneekloth

July 27, 2021

I know my question is not gonna be a black or white answer as it probably depends on water quality and other factors too. But is there a volume of water flow rate per amount of surface area of your bio filter? Just using random numbers as example. Say 50 gallons a minute for 5000 square feet of surface area?

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