You’re listening to Fish Grow Plants—A podcast all about practicing and sharing the love of aquaponics; hosted by Logan Schoolcraft.
Hello, and welcome to Fish Grow Plants! In today’s episode we’re answering the question, “What are the types of aquaponic systems?”
I wouldn’t call myself an expert at anything, really, but I have to keep remembering that not everyone has been enamored with aquaponics as long as I have. The problem with that? Well, I tend to forget that the things I take for granted, or consider the basics, are still new to people who are hearing about aquaponics for the first time.
When I sit down to write and record these episodes, I have all the current thoughts and concepts I’m thinking about that I’d like to share and dive into, but I have to pull the reigns back. I have to remember that it’s good to bring people up to speed in a reasonable manner. There’s no need to have you see the inner depths of my mind…I wouldn’t want anyone to have to do that routinely!
So, before we can dive into arguments over which type of system is best and the debate of the enduring qualities of each, we need to be clear about the types of systems themselves.
A word on assumptions here. I’m assuming that when we say aquaponics, we’re talking about a closed-loop, recirculating system, also known as a coupled system. This means that the water that goes into the fish tank, is the water that goes into the plant beds, is the same water that goes back to the fish tank. Essentially, the water goes in a circle and is not dumped or removed from the fish tank. (We’ll talk about decoupled systems in another episode.)
Alright, I think that’s enough preamble to get us started. Shall we dive in?
If we don’t count combinations of system types, or the extremely unique types, I think there are essentially 4 or 5 types of aquaponic systems.
One of the most commonly used commercial systems is Deep Flow Technique (DFT), aka Deep Water Culture (DWC), aka Deep Water Technique (DWC). This method is pretty much as it sounds like—it has a culture, or a crop, that grows on a deep water, or flow, of nutrients. The word deep may sound deceiving at first, but it is usually no more than 10 or 11 inches deep in reality. I’ve read of some systems using as little as 3 inches and I currently use a water depth of about 8 inches, give or take the water level.
To hold plants on top of the water, they are usually started, or transplanted into net, or slit, pots approximately two inches in diameter. These pots are then placed into corresponding holes made into a Styrofoam raft that floats on the water. The Styrofoam acts not only as a holder of plants, but it also insulates the water and blocks light from getting to the nutrient rich water below.
Additional air needs to be added to this depth of water to ensure the roots can get the oxygen they need. If not, they will drowned just like us.
Deep Water Culture is good at holding a stable temperature and nutrient level across its entire surface area. It is very easy to manage and cycle plants through the system. It is almost a plug and play system where the rafts are installed with young plants and rafts are removed with old ones. This ease of crop installation and removal is one reason why it is so favored in a commercial setting.
But there is also another widely used technique on various levels. That is the Nutrient Film Technique (NFT). NFT, much like the name Deep Water Culture, is just as it sounds. There is a film of nutrients supplying the plants what they need. This is usually accomplished with a PVC pipe, or similar structure (think gutter), set to a slight angle such that a small stream of water, i.e. a “film”, can slowly trickly down its length. On the top of this pipe, there are holes that hold net pots or starting blocks that allow the plants to reach the water, but not clog the pipe and restrict the flow further down the pipe.
NFT is commonly used in large hydroponic operations where the air temperature is closely controlled. Due to the small amount of water, temperature fluctuation are more impactful on this system. Also, a lack of power to control temperatures or water flow can be a real problem, if not solved very quickly.
As you can guess, this system is ideal for small, quick growing crops, since larger plants may clog the pipes and gutters with their roots. That doesn’t mean there are not ways around this, but it does mean there will be more hardware to mitigate the issue.
Ok, the next type of aquaponic system may be the one you’ve heard of and seen the most. That is the Media Filled Bed system, or technique. Again, these names are very descriptive, and the Media Filled Bed is simply that. A bed, i.e. a waterproof container that holds an inert media. The media supports the plants and acts as a filter and biological surface area for the bacteria in the system.
The media you may see most often in pictures online is expanded clay pellets. There are a number of substitutes, such as gravel, and certain types of plastics, but the critical part to remember is that this media must be inert, not reactive, or corrosive, or harmful. Ask me. I built a system and filled it with local gravel. I thought I had tested it, but not well enough. There was so much calcium and soft “rocks” that my system pH was always over 8.0 even though I was dumping in a large amount of acid to counter its effects.
There are many ways to run these media beds. You may have heard of the constant flow method, which is just as it sounds—water is constantly flowing over the media. Then there is the flood and drain method; again, just as it sounds—water floods the media for a time, then is drained; and the cycle repeats over and over.
This method may be the easiest for a beginner to try. I feel it lends itself to an aquarium addition quite easily and could look very much like an ordinary house plant setup.
Alright, our next system takes to the air. Not in flight, but in root. I’m talking about Aeroponics. Aeroponics is growing plants with their roots in the air! Not just any air though. Think of it more like a steamy bathroom—the air is filled with humidity, water is all over, and you can’t help but feel damp. For a simple concept, think of a waterproof box that has a plant sitting in a net pot on top. And inside that box is a pipe with a nozzle on it. When a timer goes off and tells a pump to send water down that pipe, it hits the nozzle and is turned into tiny, tiny droplets that coat the entire box—including the roots of the plant.
This system is highly sensitive to temperature fluctuations and loss of electrical power since letting the roots go too long without water will mean death much quicker than other methods.
Here too, this system is good for small and sensitive plants that like an “airy” feel to their root zone or cannot take much water at one time.
I would not call aeroponics a beginner’s method, and I have not tried my hand at this system yet myself. I’m more of a low-tech, keep my plants safe kind of grower, but that doesn’t mean aeroponics can’t be your ticket to amazing plants!
The last method I’m going to mention is Vertical Aquaponics. I was kind of hesitant to list this as an aquaponic system type. Why?
Well, depending on how you define and actually carry out this method, it could very well be just a combination or variation of the methods we just talked about.
For example, if you put some “shallow” Deep Water Culture troughs on some heavy duty shelving, does that count as vertical aquaponics? How about staggering some NFT gutters along a wall; does that count as vertical aquaponics, or just a vertical variation on NFT?
Vertical aquaponics is unique in several ways due to the challenges it presents. Such things as weight of materials (especially water), light and light exposure, and access—the literal act of being able to reach up and do what you need to—are all challenges. There a few good ideas out there, but they all seem to be slightly less than ideal, or are pretty expensive and high-tech or energy intensive to meet these challenges.
I think there is good potential for vertical aquaponics, so I wanted to list it and let you make up your mind if it’s worth pursuing.
Well, there you have it. The 4 or 5 types of aquaponic systems. Again, just a quick run down, they are:
Deep Water Culture (DWC)
Nutrient Film Technique (NFT)
Media Filled Bed
And remember, these are your basic coupled, or recirculating, systems; and they can be combined in numerous styles and forms.
The take-away questions you have to ask yourself when deciding which system is right for you will include:
How much space to have?
Can I put a lot of weight in the space I have?
Do I have good lighting, or will I have to supplement?
Can I control the air temperature reliably around my system?
And one of my personal favorites, if it’s a small indoor system is: can I get the floor wet, or will that be a big problem?!
Well, you can probably tell there are a lot more questions that will flow from these, but hopefully you now have a good idea the type of aquaponic systems and which one, or combination of types are appealing to you.
Questions! Let me have them! Do you need clarification, more information, or maybe you just have a tangent thought—send all your thoughts my way. See the website fishgrowplants.com for episode details, or just fire off an email to firstname.lastname@example.org and I’ll get back to you.
So, was this episode good, bad, ugly, or other? Let me know! Comment, email, smoke-signals it doesn’t matter! I love to hear from you. Your feedback is immense, and I am always grateful for it. Likewise, thank you for taking the time to listen and share your thoughts. Have a wonderful day.
This has been another episode of Fish Grow Plants—the podcast all about practicing and sharing the love of aquaponics; hosted by Logan Schoolcraft.