Aquaponics. A virtuous loop that delivers a lot of food.

Aquaponics refers to any system that combines conventional aquaculture (raising aquatic animals such as snails, fish, crayfish or prawns in tanks) with hydroponics (cultivating plants in water) in a symbiotic environment. In normal aquaculture, excretions from the animals being raised can accumulate in the water, increasing toxicity. In an aquaponic system, water from an aquaculture system is fed to a hydroponic system where the by-products are broken down by nitrification bacteria into nitrates and nitrites, which are utilized by the plants as nutrients, and the water is then recirculated back to the aquaculture system.

As existing hydroponic and aquaculture farming techniques form the basis for all aquaponics systems, the size, complexity, and types of foods grown in an aquaponics system can vary as much as any system found in either distinct farming discipline.

The video below shows how a big operation functions. These guys rely on big filters. In smaller, indigenous and more ergonomic systems, worms are use to filter waste from the aquatic animals. Worms break down the solid waste from the fish, and excess roots and other materials that plants slough off, and make them more bio-available to the plants through their excrement—vermicompost. This additional metabolic layer avoids both the requirement to filter out solid waste and the requirement to frequently clean out their grow beds. A 12-in. deep grow bed with a healthy population of worms will probably only need to be cleaned out every few years.

Vermicompost, and the tea that results from soaking vermicompost in highly oxygenated water (such as the conditions found in an aquaponic grow bed), have been studied extensively by the Soil Ecology Lab at Ohio State University and found to aid in the following pest and disease issues:

  • Suppresses plant diseases, including pythium, rhizoctonia, plectosporium and verticillium
  • Suppresses parasitic nematodes
  • Suppresses insects and pests such as tomato hornworms, mealy bugs, spider mites and aphids

Here’s the transcript for the Urban Farming Guys’ video below.

“Welcome to our phase one greenhouse aquaponics system, set up to grow 1,000 fish. We’ve got six of these tanks plumbed together, each holding various rates of growth of fish for continuous harvest. In the back, we got our vortex filters I’ll tell you about later. But, first, let’s get some basics. Aquaponics is the merging of two farming technologies–you’ve got hydroponics & aquaculture. Hydroponics is growing plants without soil in water, like we got here. Aquaculture is fish farming. This is a symbiotic relationship, where the fish fertilize the plants with their waste. The plants use that fertilizer, soak it up, & send the water back clean to the fish to re-use. Some of the other benefits of aquaponics are the free organic fertilizer we get every day, the optimal growing environment for the plants, & the freshest fish & veggies to your plate on the earth.

So, the best way to learn aquaponics is to learn the principles. Once you figure out the principles, you can build the system any way you like to fit your goals using whatever materials you can find in whatever country you’re in. So, whether you wanna build a small basement system with 40-gallon totes that’ll give you salad greens every day for your family..or if you wanna build a backyard system with a thousand fish & multiple grow beds..or a large scale production system–it’s all the same principles.

So, principle #1: get connected. Post any questions you have in our forum. We wanna help you. Visit our growing database of technical information at Join us; there’s a bunch of like-minded people there who wanna help you out.

Okay, that wasn’t a principle. But, the most important thing you need to be concerned with when you’re building your system is water quality. You wanna keep the ammonia low, the oxygen high, & the temperature right. We’re gonna show you just how that happens. A lot of people ask how many pounds of fish can you put in your system per gallon of water? Well, fish excrete toxic ammonia. The answer to that question is highly determined on how quickly your system handles that ammonia. So, rather than flush that water down the drain, aquaponics takes advantage of the ammonia. It’s called the nitrogen cycle & it takes place right here. It’s all about building your system to host the most healthy bacteria. The fish excrete the toxic ammonia compound. The bacteria immediately eat the ammonia, turn it into nitrite. Another bacteria comes along, eats the nitrite, converts it into nitrate which is then absorbed by the plants as fertilizer.

So, that poses two questions: how do you build your system to host the most bacteria? & where do you get that bacteria in the first place? The amount of bacteria that your system can host is directly proportionate to the amount of surface area your system has. This particular bacteria needs surface area to colonize. That’s what the rocks are good for..Besides stabilizing the plants, they create a huge amount of surface area. & you can increase this in several other ways–you can build a trickle filter, a sand filter, we built a bead filter with 100 pounds of beads tumbling around, creating a massive amount of surface area. We’re gonna talk about these in the forums. Come check it out, ask questions, we’re gonna help you out with this.

So, where do you get the bacteria in the first place? Well, it’s there, you can’t avoid it. Once you start adding ammonia to the system, the bacteria will start to colonate..which you can speed up the process by taking a filter or some rocks from an existing system & introduce it to the new system to get going. Next, we’re gonna talk about can go as big or as small as you want on this..

These guys right here are our vortex filters. Retail, they’d be about $4,000 apiece..DIY version, about $100. You might be able to do it for cheaper. We’ve got a 55-gallon drum with a cone built into it down into a shower drain. Out here, you can pull off your fertilizer every day for your garden. I’ll show you about that. We’ve got an incredible fertilizer. We have a pretty intense system so we built some really intense filtration. But, you’ll wanna think about these processes.

Stage One, you wanna settle out as much of the solids as you can before you send it to your mechanical filter so you don’t have to change your filter pads all the time. So, we built this vortex filter where the water spins real slow, the solids settle to the bottom, we pull them off as fertilizer every day.

Stage Two, whatever solids sneak by get caught in four filter pads so that the only thing left to filter now is the ammonia.

Stage Three, is the biological filter. It’s where you create a lot of surface area for bacteria to grow. Ours is a bead filter. You might do a sand filter or a trickle filter. After stage three, the ammonia is turned into nitrate. It’s pumped up to the plants.

Stage Four, the plants use the nitrates & send it back clean. & you can do this on a much simpler level. We wouldn’t even need the vortex filters if we just had 100 fish instead of 1,000. The rocks & the grow bed would do most of the biological filtration & we’d just to have to clean it out, whatever solids got caught up in there. But, we are on a mission to create organic fertilizer & harvest it.

We just pulled some concentrated fish manure out of our filtration system & we’re gonna test it. We’re gonna take it up to the University of Missouri & find out what’s in it. We know it’s full of nitrogen, it’s great for the garden. But, is it everything? Is it missing anything? You know— How far do you spread it? How much do you need to dilute it? We’re gonna get the results from MU & get back to you in the next episode.

We got those results back from MU & it looks to be an incredible fertilizer. 9-6-2. Full of micro-nutrients, potent enough to fertilize about twenty tomato plants a day, come back & fertilizer twenty more. We posted the full analysis in our database on the website. Come check it out. & lastly, if you don’t really care how it works & you just wanna download some plans & a part list so you can build it, we got a growing database of open source information.”