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Ultimate Comprehensive Guide to the Media Based Technique in Aquaponics

aquaponics media based technique
Image Credit: How to Build an Aquaponic System - Chop & Flip IBC Build, Rob Bob's Aquaponics & Backyard Farm.

Aquaponics is an eco farming technique that couples hydroponics with aquaculture to enable plants and fish to be raised together in the same closed-loop system. This sustainable farming method recreates the important processes that occur naturally in the wild so the plants and fish can thrive in symbiosis together in your man-made ecosystem. One of the first things you’re likely to find out when researching aquaponics is that there are three main techniques, Media Based Technique, Deep Water Culture (DWC) a.k.a. Floating Raft Method, and the Nutrient Film Technique. Each has various configurations that come with their own pros and cons, therefore it’s important to understand how each method works so that you can select the most suitable aquaponics setup for your needs. In this article we’ll take look at the Media Based Technique in Aquaponics, what makes it different from the other methods, and how the system actually works.

Table of Contents

What is the Media Based Technique in Aquaponics?

The Media Based Technique, also known as the Flood Drain method or simply media bed aquaponics, refers to aquaponics systems that utilizes traditional grow beds, in which the soil is replaced with an aquaponics grow medium such as clay pellets, lava rocks or gravel; hence the name.

Nutrients are provided by a process known as nitrification; the conversion of ammonia present in fish waste, into nitrogen (nitrates and nitrites) that plants can feed on.

Nitrification relies on the addition of beneficial bacteria, which colonize in the in the biofilter for other types of aquaponics set ups, however in media based systems the chosen media forms the mass for these colonies, here the microorganisms can then perform this all-important process that feeds the plants and helps to filter the water.

The media based aquaponics method is commonly used for home systems, set up either in or outdoors, largely due to the ease with which DIY systems can be constructed, and the cost of these DIY home built systems being one of the cheapest options to get an aquaponics system up and running.

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How Media Based Technique Works

The media based methods works by pumping water from the fish tank, through a solid separator filter and into the grow bed where the plants are supported by a grow media. Here the grow media itself acts as a biofilter, although some systems opt to install a separate biofilter alongside the solid separator in pair of tanks known as the mineralization stage, or filtration tank. 

The grow media/biofilter is responsible for the nitrification process. Nitrification refers to the conversion that transforms fish waste into plant food. This is carried out by beneficial bacteria from the Nitrosomonadaceae family, which include Nitrosomonas, Nitrosococcus, Nitrospina, Nitrobacter, Nitrospira, and Nitrococcus. In performing this task the biofilter provides part of the filtration stage.

These essential microorganisms colonize in the grow media-biofilter, and other surfaces of the system, where they can then convert ammonia into nitrites and nitrates, which the plants can use to feed on.

Just like any aquarium, you’ll need to feed and take care of the fish to keep them healthy and alive,. However this will be the only food source you need to add manually since the plants will feed off the nitrogen produced by nitrification stage.

From the fish tank the water is pumped through a solids separator and into the fill the grow bed where the nitrification conversion will take place. As the grow bed fills up the nutrient rich water has ample time to deliver food to the plant roots, before it’s automatically drained by the bell siphon

By passing through the solids separator to remove larger waste particles, and through the biofilter where the beneficial bacteria helps to feed the plants and provide further filtrations, the water becomes sufficiently cleaned to be recirculated back into the fish tank. 

As noted, the bell siphon regulates the water in the grow bed so that it floods and drains. Once the water level reaches the predetermined point set by the top of the bell siphon, the device then fires and starts to drain the water automatically.

Depending on the setup, water can then be drained directly back into the fish tank, or into an additional sump tank. This will be determined by several factors such as whether you’d like a visually pleasing  aquarium, or simply want to keep the fish for the purpose without much consideration for aesthetics.

How and where you choose to install the filtration stages will also become a factor. Here you’ll need to consider whether or not to use the grow media as the biofilter, or a separate device, and where you’ll put the solids separator; either ogether with the biofilter in a mineralization tank, or separately between the fish tank and grow bed. 

Once the water has been drained back into the fish tank the cycle is complete and will repeat over and over again until it’s physically prevented from running.

Check out the video below for a more in depth dig into the flood and drain method used in media base aquaponics.

Advantages and Disadvantages of Media Based

Each type of aquaponics technique provides its own benefits and downsides. Making the choice of which method to use will generally come down to how these pros and cons stack up against your specific situation.

Advantages of Media Based Aquaponics

Suitable for All Types of Plants: Unlike NFT and DWC aquaponics, which offer very little support for plants, media based systems use an aquaponics grow medium in place of soil, and this provides more room and support for larger plants to grow.

Excellent Nutrient Delivery: The flood and drain technique utilized by media based systems provides effective delivery of nutrients thanks to the flooding phase of the grow bed media, which allows adequate time for roots to soak up these nutrients.

Simple Setup & Operation: Media based systems are relatively easy to build, and setup. They’re also easy to operate as once the bell siphon is firing correctly, the water will flood and drain automatically.

Easier Biofiltration: The grow media can double up as the biofilter thanks to the large amount of surface area the medium provides for the beneficial bacteria to colonize. This means that media based system don’t necessarily require an additional separate biofilter.

Easy Cleaning: The flood and drain process naturally rinses the grow media as it repeats. So as long as the filtration stage is running optimally, cleaning can be a simple wipe down, or a partial water change.

Easy DIY: The design of media based systems can be easily constructed from off-the-shelf components with very little work required for the amount of customization possible. Not only does this make it straightforward to build your own, it’s also inexpensive.

Disadvantages of Media Based Aquaponics

Scalability: Although it is possible to expand your media based aquaponics system, the large amount of bulky, heavy grow media makes it slightly less viable, and a little more challenging, to scale up when compared with other aquaponics techniques.

Blockages: Depending on your choice of grow media, clogging and blockages can become a problem, especially with more porous materials. To avoid this problem ensure the filtration stage is running effectively and that your system is kept clean.

Weight: It goes without saying that the additional grow media adds extra weight. Whilst this might not always be a problem, it can certainly become a factor if you’re unable to install the system directly onto hard, solid flooring.

Cost: Of course, all this extra grow media does come at a higher price. However, grow media can be reused so this is typically just part of the initial setup costs.

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Components of Media Based Technique Aquaponics System

Fish Tank
Essentially an aquarium, the fish tanks houses the aquatic life that will produce the waste that will become the fish food.

Water Pump
Water pumps must be highly reliable as they’re required to run consistently, 24/7. This is crucial to the survival of the ecosystem, because if the flow stops, so too will the lifeline keeping your plants alive. For this reason it’s advisable to buy the most reliable, high quality pump you can afford.

Grow Bed
This will contain the grow media in which your plants will be placed. Grow beds can be made from a range of recycled materials such as Intermediate Bulk Containers (IBC), wooden troughs or in fact any container that meets your sizing specifications, and is strong enough to hold the grow media and plants.

Grow Media
Several types of grow media are suitable for aquaponics grow beds. These include clay pellets, expanded shale, lava rocks and/or gravel. Since this is essentially your plant’s home, as well as the place where a majority of the beneficial bacteria will colonize, it’s a good idea to use the best quality grow media you can afford.

Bell Siphon
Perhaps the most important component in media based aquaponics, the bell siphon regulates the water level in the grow bed, which drains when it reaches a predetermined level and allows the system to run automatically.

Amazon has a range of ready made bell siphons here.

Biofilter
As mentioned it’s possible for media based aquaponics to utilize the grow media as the biofilter. Alternatively the biofilter can be installed in a separate tank between the fish tank and the grow bed.

Solid Separator
Solid separators remove the larger solids of the fish waste but isn’t optional, unlike the biofilters of media based systems that can be removed in place of the grow media. The solids separator must be installed between the fish tank and grow bed. In cases where the biofilter is separate, it’s common to construct a twin chamber tank to house both filtration stages together in what is known as the mineralization stage.

Plumbing Network
Depending on the configuration of your media based setup, the plumping network required to connect all the components will likely be less substantial than other systems, especially in setups where the bell siphon drains directly into the fish tank.

How to Set Up Your Media Based System

Location: The location of your system is always an important factor. Depending on where you live, the weather can have a huge affect on how things function. And where you choose to place the system will no doubt affect temperature and amount of light it recieves.

You’ll want to consider the duration of light the system is exposed to, together with the water temperature and the ambient temperature of the surround air.

Be sure to give the plants at least 6-8 hours a day, which may require the use of grow light and/or shading. Also ensure the water and air temperature is suitable for the living organisms in your ecosystem.

Selecting Grow Media: Another highly important part of the process, choosing the right grow media will depend on a few factors. Certain plants may prefer specific types of aquaponics grow media, as may the beneficial bacteria, therefore you’ll typically want to select a type that suits these requirements. For this reason it’s advisable to purchase the highest quality grow media as possible.

Selecting Plants: One of the main benefits of media based systems is the ability to support almost any plant, that will fit. Some of the best plants to grow include leafy greens, herbs, fruiting plants, root vegetables and flowers.

Selecting Fish: As with most aquaponics systems, it’s generally advised to raise a hardy fish that can tolerate changes in its environment to give you the best chance of keeping them healthy and alive. Popular fish for media based setups include tilapia, goldfish, trout, perch and catfish.

Preparation Cycling: No matter the system, allowing it to cycle properly prior to planting is extremely important. This gives time for the beneficial bacteria to colonize in large enough numbers to perform the nitrogen cycle effectively. Without sufficient time for this to occur, the beneficial bacteria will be unable to carry out its task and the system will fail before it’s even started. Cycling your aquaponics setup can take anywhere from 4-6 weeks. So be patient, and monitor daily.

If you’d like to find out more about cycling and the nitrification process, why it’s so important and how you can ensure it’s complete before you being growing, then check out our in-depth article on the Importance of Cycling Your Aquaponics System.

media based aquaponics
Image Credit: 3 Aquaponics Systems - New Build Update, Rob Bob's Aquaponics & Backyard Farm.

Buy or DIY

Buy: Media based system, like most aquaponics setups, are becoming more popular all the time, and as a result there are now more options than ever if you’re looking to buy a complete, all-in-one system that’s ready to go.

Of course buying a brand manufactured product is usually more expensive than taking the DIY route, however the setup will no doubt look more professional, and should have any kinks ironed out so the product itself doesn’t give you additional problems.

For those who aren’t too DIY inclined, buying a ready made aquaponics system will not only save time, it can also give your plants and fish a better chance of survival, as well as greater yields, especially when compared to poorly made DIY setups.

DIY: Fortunately DIY media based aquaponics can easily be constructed from off-the-shelf parts and recycled/repurposed components. For example, a popular way to build these setups is by chopping an IBC in two and flipping one half over to become the grow bed, then placing it on top of the remaining half, which in turn becomes the fish tank.

In fact, this method has become popular enough to receive its own term, ‘the CHOP and Flip aquaponics method.’ But whether you choose to use an IBC or some other form of grow bed, the DIY method will allow you to customize the parts to fit your needs. it can also save you money over pre-assembled, all-in-one solutions that. A quick aside here, the term CHOP doesn’t actually refer to action of slicing an IBC in two, in fact it’s an acronym which stands for Constant Height One Pump.

How to Maintain Your Media Based System

Daily Monitoring and Maintenance

In order to keep your aquaponics system in check and operating smooth, there are a number of parameters you’ll need to check on regular basis; some daily, some multiple times per day.

Bell Siphon: With the task of automatically regulating water level and draining when necessary, ensuring the bell siphon is filling and firing properly is extremely important. Without it the system will flood, or may not fill, both of which will cause the system to collapse in a relatively short amount of time. There are several ways to construct a functional bell siphon, as well as a few tips to ensure it works effectively.

If you’d like to find out more about bell siphons, and how to make your own DIY version, head on over to our article describing in depth how you can achieve this. Alternatively a range of pre made bell siphons are available on Amazon.

pH: One of the main factors that can cause your plants and fish to die, the pH level will require regular monitoring, and adjusting when needed. Different species of plants and fish prefer varying levels, which is one of the reasons why not all species are suitable for aquaponics.

Dissolved Oxygen (DO): Both fish and plants require enough oxygen to be present in the water. Should you need to increase aeration in the system you can install an air pump and air stone, a waterfall, fountain, or a series of cascading steps that agitate the water to create higher concentrations of DO.

Plant Health: Plants are often the first to give any warning that something might be amiss. Be sure to check your plants regularly for any signs of stress, nutrient deficiency and/or pests. And remember, the earlier you can spot and fix any of these problems the better.

Fish Health: Fish will also begin to show signs of stress or disease if any issues arise or the conditions simply aren’t keep right. So again, be sure to monitor your fish for signs of stress and/or disease, and act immediately if you spot any problems.

 

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Pests & Disease

Preventing and pests and disease is a problem that can arise if the system isn’t monitored and maintained properly. The leading causes of pests and disease in aquaponics results from nutrient deficiencies, and/or contamination from the outside world.

Algae Growth: Algae thrive in the same conditions as the plants and fish within your aquaponics system. But as algae begins to flourish, it essentially starts to suffocates the system. To prevent this you can limit the amount of sunlight that reaches the setup and refrain from using opaque building materials.

Root Rot: Root rot can stunt the growth of plants and eventually cause them to wither and die. To avoid this ensure your aquaponics system is sufficiently aerated, and if your plants begin to develop this disease, you can add beneficial microorganisms that will help combat the root rot.

Pests: Pest can be attracted to any grow, so you’ll want to keep a close eye out for any signs of infestation. To prevent bugs from making your plants their home, try using neem oil or a citrus-based insecticidal oil. Or if you already have an infestation then employ the help of natural predators like aphid midges larvae, ladybugs, or lacewigs, all of which will attack and eat the unwanted pests.

What is the Nutrient Film Technique in Aquaponics Vertical

How to Prune Your Aquaponics Crops

Although media based aquaponics has the ability to grow larger plants then other aquaponics methods, you may still need to prune and trim the leaves to prevent over crowding or the plants growing too high.

To achieve this you’ll need to remove dead and/or damaged leaves, encourage branching in certain areas, and trim where necessary to prevent the plants from overgrowing.

Pruning plants can help keep them healthy and free from disease. It can also make monitoring and maintenance easier as you’ll be able to see and reach the plants with less interference.

How to Harvest Your Aquaponic Crops

The time to harvest different species of plant will vary, so it’s important to know roughly how long the species you’ve chosen will need to mature. In general, you’ll know the time to harvest is right when plants reaches full maturity, any fruits are almost ripened, or flowers start to blossom.

Harvesting not only gives you the yield you’ve been patiently waiting for, it also promotes new growth cycle so you can get the most out of your media based aquaponics setup when performed at the right time.

How to Optimize Media Based System Performance

There are several handy tips and tricks you can use to optimize your media based aquaponics setup. Some of the most common bits of advice include:

Balance Fish to Plant Ratio: No matter the size of your system, the ratio of fish to plants is important. With too few fish the nitrification process will not convert enough food for the plants, and with too many fish and to few beneficial bacteria, the toxicity of the water can rise to unsafe levels. Although different species have different requirements, the general rule of thumb is to use a ratio of 1:2 / fish:plant.

Lighting: Since both the plants and fish, as well as any unwanted algae growth, all require lighting, its important to provide enough for the former, but not for the latter. Where possible try not to let any more light than is necessary reach the system, this will limit algae growth whilst supplying enough for the fish and plants.

Stable Environment: With any aquaponics systems the temperature  should be kept stable/consistent. Plants generally enjoy temperatures between 70-75°F / 21-24°C, whereas different fish species can survive in a wide range of temperatuers, so be sure to research this when choosing your aquaponics fish.

Oxygenation: Another key factor in the health of your aquaponics system is oxygenation. So you’ll need to make sure enough dissolved oxygen (DO) is present the water to so the fish, plants and microorganisms can thrive. Should you need to increase aeration in the water you can add an air pump and air stone, or install water features such as waterfalls, fountains, or cascading steps that help to agitate the water and produce more DO.

Combining Techniques: The media based method can be coupled with other aquaponics techniques to maximize yield. In addition media based system can function alongside NFT and DWC setups to allow for more choice in customization.

In Conclusion

Media based aquaponics systems are popular option for sustainable farming at home thanks to the versatility, straightforward setup, easy maintenance, and the ability to support a wider variety of plant species than is typically suitable for NFT or DWC aquaponics techniques.

In addition, media based systems are relatively easy to build, with several different DIY approaches that allow the system to be tailored so it meets your requirements.

But perhaps the biggest selling point for media based aquaponics is the larger number of plants it can support, an option that can be limited when wanting to grow fruiting plants in NFT or DWC systems.

So whether you’re an expert, intermediate, or beginner in aquaponics, the media based system can be a great choice for any home setup.

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