How To Make Your Own Aquaponics Filter (6 Easy Steps)


While water filters are not necessary for an aquaponics system, adding one can improve the health of your fish and plants. There are several potential filters that you can use to enhance an aquaponics system. However, if you’re planning to build one yourself, it’s better to focus on biofiltration systems.

Here’s how you can make your own aquaponics biofilter in 6 simple steps: 

  1. Gather supplies. 
  2. Drill holes in the bucket. 
  3. Properly place your biofiltration media. 
  4. Add the mesh and screen. 
  5. Install the filter. 

Along with these steps, there are some advanced techniques you can use to filter your aquaponics system. Keep reading if you’d like a thorough guide that expands on the basic steps above and adds some advanced aquaponics filter information.

1. Gather Supplies

The consensus on aquaponics systems is that they don’t require significant intervention because they replicate a symbiotic design that can be found in nature. The fish, plants, and bacteria can thrive off one another without constant adjustments and monitoring from the gardener. 

However, adding a biofilter can strengthen the system and improve the quality of the environmental conditions you create. 

To build your biofilter, the first thing you’ll need to do is gather your supplies. Getting your supplies together before you begin your DIY project will help you prepare for the task and save time as you go. 

The following list includes the tools and equipment you’ll need to build your biofilter: 

  • Electric drill 
  • Screws 
  • Uniseals 
  • PVC pipe 
  • 5-gallon (23-liter) bucket 
  • Screen 
  • Mesh 
  • BioBalls/Expanded Clay 

Most of these tools you may already have on hand at home or can purchase for a relatively small amount at most local retailers or online, depending on your preference. 

The most expensive item on the supplies list is the electric drill. While you may get around using this tool, it will make it easier for you to complete the first step of building your DIY biofilter. 

Screws, mesh, a 5-gallon (23-liter) bucket, and a screen are all items that you can likely find at your local hardware store for reasonable prices if you don’t already have them on hand. 

You can substitute some of these items for alternatives you may already have at home. For example, a biofilter can be made out of almost any container. There are even some DIY tutorials that use empty 2-liter (half gallon) soda bottles. Using a soda bottle seems like it would be too small to be successful, though, so I recommend a 5-gallon (23-liter) bucket. 

Depending on your preferences, you may even want to use two or three 5-gallon (23-liter) buckets. Using more buckets or containers will increase the filtering medium that the water passes through, thus improving the filtering of the water. 

Schematic diagram of an aquaponics NFT-system that has a radial flow filter and a biofilter

2. Drill Holes in the Bucket

The next important step in creating your biofilter is preparing your containers, in this case, buckets.

Drill a hole in the 5-gallon bucket. If you’ve opted not to use an electric drill, you will need to use another tool to create the hole, like an Exacto knife or something similar. Always follow manufacturing safety guidelines when using power tools or sharp objects. 

You need to create a hole in the bottom of the bucket. Make sure to place the hole strategically, as this is the area where the water from the fish tank will flow. The hole should be about ⅞” (2.2 cm) in the bottom center of the bucket. 

If you’re using multiple buckets, you’ll want to drill a hole in the bottom center of each one. If you’ve opted against using a drill, a spade bit or a hole saw could also be effective at this task. 

If the hole’s edges are rough and jagged when you finish, clean it up by scraping the edge with a sharp knife or file. 

Make sure to make the hole large enough for the PVC pipe to attach to the bucket. Use the uniseals to seal the area around the hole and the pipe to prevent water leaks. You could also use O-rings on the inside of the bucket and a coupling. Simply tighten the two fittings until the O-ring begins to compress. 

Once you’ve drilled your hole on the bottom of the bucket, you will drill another hole on the top or lid of the bucket. This hole is where the water from the biofilter tank will drain into the plant culture bed or grow media, depending on your aquaponics setup. If you have multiple buckets, the water will flow between buckets. 

Again, you’ll want to seal the area so that there are no leaks from the pipe and the bucket. 

With this method, the bucket will act as the water tank for the filter. 

3. Properly Place Your Biofiltration Media

The next step is to place the biofiltration media strategically. For this DIY filter method, you need to place the media at the bottom of the bucket.

BioBalls or expanded clay are your best picks for biofiltration media. You don’t have to buy both—just pick the one you prefer or the one you can find for purchase. 

Each media option has similar benefits. One benefit of the expanded clay (available on Amazon.com) is its porous nature. Expanded clay pellets absorb moisture and allow the water in the system to drain well from the plant’s roots. 

Besides having superb moisture absorption, expanded clay pellets also absorb all nutrient solutions. This absorption, together with adequate spacing, allows this media to achieve high drainage, which leads to maximum air circulation. Air circulation is crucial for your aquaponics system—it ensures that the plants receive as much oxygen as possible. 

Expanded clay pellets have other advantages, such as longevity. In addition, you can wash and reuse them as many times as you need to. To learn about more benefits and potential downsides of these media, check out this article from Epic Gardening. 

On the other hand, BioBalls are tiny round plastic balls that provide excellent biological filtration in your system. They house bacteria and have lots of dips and divots to allow for their growth. To learn more about BioBalls, check out this article from Fish Lab. 

Once you’ve placed your media, you’re ready for the next step. 

4. Add the Mesh and Screen

The mesh in this DIY filtration system works to filter out and screen smaller waste particles. Add the mesh (available on Amazon.com) to the area where water will pass through to trap any remaining solids that reach the biofilter. 

The mesh and the biofilter screen add to the biofilter’s filtration capabilities. In this video by Iowa State University, you can see exactly how they place the mesh and the screen. This video also describes the use of BioBalls as growth media: 

After you’ve added the mesh to the filtration, you secure the screen on top of the mesh to filter out bigger, more solid wastes. 

5. Install the Filter

Finally, you should install your biofilter tank between your fish tank and grow media to begin the filtration process.

This step will look a little different depending on how you designed your aquaponics. You’ll likely install your filter outside the tank. You can use a pump to get the water up from the fish tank into your filter, and then use a PVC to take the filtered water to your plants. With the right setup, you can also let gravity do the work for you.

Types of Aquaponics Filters

Aquaponic systems allow horticulturalists and gardeners to grow food, vegetables, and other plants alongside fish and bacteria without the use of soil.

Aquaponic systems can be developed by professional commercial growers and novice hobbyists alike. The size and complexity of your system will greatly depend on your skill and how used you are to this style of farming. With most builds, you’ll require the use of an aquaponic filter. 

Aquaponic systems allow growers to grow plants that live off the wastes of healthy fish living in the system, supported by the excrements of bacteria. The plants help the fish and bacteria stay healthy by filtering water through their roots.

Aquaponic systems mimic processes that already occur in nature by allowing plants, fish, and bacteria to flourish in a symbiotic relationship. While a filtration system isn’t always necessary for an aquaponic system, having one in place can add to the quality of the overall system and its water. 

There isn’t necessarily a one-size-fits-all filtration system for your aquaponics set-up, so you may need to explore different types to find what works best for you. There are three main types of filtration for aquaponic systems: 

  • Biological filtration 
  • Chemical filtration 
  • Mechanical filtration 

Quality water is essential for healthy aquaponic systems. Maintaining clean and pure water will ensure that all of the aquatic critters in your system keep thriving. 

Some aquaponic techniques for filtration include: 

  • Flood and drain method 
  • Drip systems 
  • Deep culture systems 

Other methods exist, but these are the most popular. For now, though, let’s dive into the different types of filtration options available for aquaponic systems. 

Biological Filtration

A biofilter, once established, will work to convert the ammonia and nitrites into nitrates. In other words, it turns waste into nutrients your plant can take in easily. Plants in your system can access the nitrates they need to grow and simultaneously clean the water for the fish in your system. 

Biofilters generally work in a three-step process, depending on the setup: 

  1. The air pump pushes the water out of the fish tank and into the biofilter. If you followed the DIY method in this article, that would be the bucket. 
  1. Inside the biofilter, the water completes the nitrification process. During this process, the beneficial bacteria in the system convert the ammonia and nitrates into nitrates. In the case of this DIY, the bacteria should attach to the grow media, and once they’re established, they’ll do their job.
  1. The nutrient-rich water flows out of the biofilter and into the plants. At this point, the plants will absorb the nutrients through their roots. At the same time, they will clean the water before releasing it back into the fish tank. 

In the DIY method outlined here, the water travels through your system through the PVC pipes. 

Chemical Filtration

Chemical filtration is another common type of filtration in aquaponics. Still, it’s not recommended to use it on a daily basis because it alters the water properties and can potentially unbalance your system. 

However, chemical filtration methods can be helpful in emergencies or problems that require quick fixes. An example of this would be using tap water in your aquaponic system and filtering it to quickly make it safe for use. 

Chemical filtration is an excellent way to remove problematic substances like heavy metals and pollutants like ammonia and other unwanted chemicals. Unfortunately, chemical filtration also can remove the nutrients needed for plants to thrive, which is why it’s not recommended to use it regularly in an aquaponics system. 

Mechanical Filtration

The final type of filtration available to aquaponic systems is mechanical filters. The sole purpose of a mechanical filter is to remove heavy solids, such as fish waste and uneaten food, from the water stream as it leaves the fish tank and heads to the biofilter. 

A mechanical filter helps prevent decaying plant roots and improves the overall water quality. Mechanical filters vary in size and shape and are usually adapted for each aquaponic set-up. The amount of fish in the system and the waste they produce should dictate the size of the mechanical filter. 

Mechanical filters are beneficial for aquaponic systems with lots of fish producing solid waste. They improve the quality of the water for all of the living components in the system. 

Because not every aquaponic system is built the same, each could benefit from a different mechanical filter. 

There are three main types of mechanical filters, and each of them works best for specific kinds of aquaponic systems: 

  • Solid separators 
  • Radial flow 
  • Baffle filter/clarifiers 

Each of these works best in different-sized systems. For example, the solid separators work best in smaller-sized systems with smaller fish. 

How To Build a Solid Separator

A solid separator, also known as a swirl filter, is helpful to remove solid wastes from your aquaponics system. The process of building it is similar to the biofilter described in the steps above. 

If you want a hands-on demonstration on how to do this yourself for less than $20, check out this YouTube video: 

How To Build a Radial Flow Filter

Radial flow filters help remove larger solids from the water in your aquaponic system. They are often used in commercial and at-home systems to remove larger waste products from the water. 

To build your own radial filter, you’ll need to gather a few supplies: 

  • A 35-gallon (132-liter) inductor tank with a conical bottom 
  • PVC coupling thread 
  • Piping 
  • Reducer 
  • A 55-gallon (210-liter) drum 
  • Drill 
  • Uniseals 
  • PVC pipe 

You will need piping in different sizes for this project. These supplies will help you create a device that will filter out large solid waste products from the water. To see how to build one, check out this video from YouTube: 

Where To Purchase Aquaponic Filters

Some of us are not the DIY type. Perhaps you have tried to create an aquaponic filter, but it didn’t work out. Whatever the case may be for you, sometimes the easiest option is to purchase an aquaponics system filter. 

Aquaculture Systems Technologies has resources and information about aquaponics systems and filters for both at-home and commercial set-ups. You can get a free quote to see how much it will cost you to install one of their products. 

Are Aquaponic Filters Necessary?

Because aquaponic systems recreate symbiotic relationships found in nature, the products produced are often healthier and more sustainable. However, precisely because they mimic natural systems, people often wonder if a filter is necessary at all. 

Water filters are not necessary for an aquaponic system, but they can increase the quality of the water and improve the health of the living elements in the system. Filters help maintain good water quality and the health of the plants, fish, and bacteria. 

In short, you don’t necessarily need a filter in your aquaponic system, but having one may help you improve your system’s efficiency, quality, and productivity. 

Plants Filter Water in Aquaponics

Growing plants and fish with an aquaponic system is excellent for producing organic food. An aquaponic system continuously reuses water by imitating naturally occurring biological processes. 

We know the basics of an aquaponic system: the waste from the fish produces natural bacteria that then converts waste into nitrate. The nitrate is absorbed by plants and provides nutrients to the fish. Essentially, the naturally produced waste is converted into nutrients for the living elements in the system. 

This process happens in stages: 

  1. The fish living in the aquaponics tank excrete waste. They also respirate ammonia into the water. Naturally produced ammonia is toxic to fish in high concentrations, so it must be removed to keep them healthy. 
  1. The ammonia in the water is processed to help beneficial bacteria prosper. The bacteria take the ammonia and convert it into nutrients apt for plants, such as nitrite and nitrate.
  1. The plants absorb the nutrients in the water. This is how the plants filter out toxic elements, such as ammonia, from the water, keeping the bacteria and fish healthy. 

What Is the Best Filter for Aquaponics?

The natural filtration method described in the section above is similar to what happens in nature. And, as previously explained, filters aren’t completely necessary in an aquaponic system. But regardless of what you choose to do, you need to think about what you will do about solid waste products in your aquaponic system. 

The best filter for an aquaponic system will depend on its size and design. Radial flow filters are the most commonly used type because they can remove multiple types of solid waste.  Any filter that effectively removes solid wastes without filtering out necessary nutrients is a good choice. 

If you don’t have a filtration method and rely on natural processes, you need to be careful to avoid clogs in grow beds due to solid waste. 

Because fish create solid wastes, farmers often choose to implement a mechanical or biofiltration method to remove solid wastes and prevent buildups. 

There are different types of solids that you need to be aware of. Some of them are:

  • Settleable solids. These tend to settle at the bottom of the system. 
  • Suspended solids. They float around inside the water. 
  • Floating solids. These tend to end up at the surface of the water.

Do You Need an Aerator for Aquaponics?

Oxygen is a crucial component for a healthy garden, and an aquaponics system is no exception. Since you’re growing plants in water, people often assume that oxygen isn’t a necessity. But air is not only needed for plants to thrive, but for the fish in the system as well

You may need an aerator for aquaponics. High oxygen levels are required for plants and fish to thrive in an aquaponic system. You can either use an aerator or water flow to disturb the surface water and increase the oxygen in the system. 

Plants and fish need oxygen to survive and flourish. This is why it’s essential to ensure that you always maintain proper oxygen levels in your aquaponic system. Different fish species require different oxygen levels to thrive, but on average, most will do well with a range of 5 to 12 mg/L (0.0006 to 0.0015 oz/gal). 

Final Thoughts

Aquaponic systems are a great way to grow produce without soil. Usually, water-based systems are more effective at growing plants than traditional soil-based gardening methods. 

Many different components go into making an aquaponic system healthy and productive, but filters are especially important. There are several different types of filters you can choose from, biofilters, chemical filters, and mechanical filters. If you have a big aquaponics system, it may be a good idea to combine mechanical and biological filters.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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