Aquaponics, by A.M. in NC


As a forward to this article, let me tell you a little about myself. I’ve been an avid daily reader of SurvivalBlog for about four years now and an avid prepper since my days as a Boy Scout. I’m 30 years old with a wonderfully supportive wife and two adorable girls. About two years ago, after being introduced to the idea of aquaponics, I started thinking about how much the cost would be to get started, how much more of my time toward prepping this would take up, and then finally how I would convince my wife that this would actually allow me to spend less time in the garden? (Insert an eye roll here.) After researching for about three months, I convinced the Mrs. that this would be cool and she approved $500 of our budget to go towards this endeavor. All in all I’ve spent about $1000, greenhouse included. That may cause a sticker shock, but that was spent over time as my setup got more complex.

I’d love to go commercial, but the FDA frowns on any food and manure coming into contact. Under normal applications, this would make sense, but with aquaponics, the fish waste (manure) is converted to usable nutrients. Plants grow at an alarming rate, with 1/10th the water, in an incredibly small space. The FDA has no problem permitting hydroponics, but aquaponics is counterintuitive to what the government says is “okay”. I think the readers here would all agree that Uncle Sam’s “We know what’s best for you ” policies aren’t always correct. The few aquaponics commercial operations out there have started in hydroponics.

I liked the article by F. B., however his/her practical application of that current setup doesn’t seem applicable in a SHTF scenario. For example, they cited too many power requirements. Think small and off grid. Below, I’m going to address what to build, why it’s done this way, and problems I’ve incurred along the way. The one thing I can say is that I’m sure someone can make improvements. There is no correct way to make a perfect set up. However, there are definitely some things not to do. 

There are four main types of aquaponic set ups and combinations that can grow lots of food. I would advise you to research each on YouTube for further explanations.  The first is vertical towers. Plants grow out of a vertical pipe, where water trickles through/over the roots. The second is media grow beds, where there is a constant inflow of water and a bell siphon to drain (aka ebb and flow). The third is a raft system where plants grow in a raft, through which the plant is grown above on a floating board and the roots hang below in the water. The fourth is NFT, or nutrient film technique. The water flows through long gutters or pipes, and plants are planted in lines sticking out of the top with roots hanging inside the pipe. All of these techniques are soil-less. The plants take in all the nutrients needed through the water. 

Growing Bacteria and Getting Up to Speed

It should be said that any system takes approximately a year to get fully functional. At first, I shrugged this off, but realistically it takes a year to get all of the chemical balances,  pH, nutrients, microbes, and bacteria where they need to be. As you know, planning ahead goes a long way. When the system is finally set up, only weekly checks of nutrients, pH, nitrite, and nitrate levels are necessary. 

The bacteriological processes that need to take place or get established are twofold. One type of bacteria converts ammonia to nitrites. The second type converts nitrites to nitrates. Nitrates are the driving factor that make plants grow. Ammonia becomes present generally through three factors. Fish produce ammonia through their gills and through fish waste. Any uneaten fish food, or solids from fish food, releases ammonia. Dead things in the system, particularly fish, will release ammonia. NOTE: Ammonia above five ppm will kill your fish!!! A good rule of thumb is to have one pound of fish per two gallons of water in your system. The amount of fish your system can handle depends on the amount of biological surface area in your system. More surface area = more pounds of fish. The more fish in the system means more available nitrates, which presents a need for more plants. I have about a dozen fish at about 30 total pounds in a 170 gallon set up. 

Not all grow media is the same! There are four main types of media used in most systems today. One, known as “miners moss”, or synthetically woven fibers, definitely provides the most surface area, however this can be expensive. This type of media is usually used in vertical towers. Next in line would be expanded shale, which is what I prefer due to it being porous in nature. Expanded shale provides much more surface area. I like pieces that are 3/4″ in diameter. It is also the most cost effective. Hydroton, or small 1/2″ clay balls, are common but also can be expensive. The cheapest option is 3/4″ gravel.  From experience, it works well, but weight is always the problem due to the amount needed for a system. I have three large bags of expanded shale in my grow bed; these bags cost me $100. It measures 40″ x 37″ x 15″ deep. The other surface area occurs on the root systems of my plants in the NFT pipes.

Something else to discuss at this point is deciding what you want to grow. Your system should target one of two things: either growing greens/herbs or growing fruit bearing fruits/veggies. Greens (lettuce, arugula, kale, collards, herbs) will require very little potassium or phosphate. The addition of those two can cause an algae bloom, which will cloud your water and suck up all the dissolved oxygen which can kill the fish. Fruit bearing plants require much more frequent testing and observation of nutrients, so as not to have deficiencies. I personally prefer the greens. I often add organic nutrients, such as Natures Nog, Epsom Salt, Kelp Meal, and Azomite at the rate of one tablespoon/week each. The fish also tolerate it well.

The fish you choose should be the ones you like to eat. If you don’t like your fish, neglect often happens and the fish die. I like catfish. Mmmmm, they’re tasty! They tolerate swings in temperature and low oxygen levels, which happen in summer when the water warms up. The higher the water temperature gets, the lower the DO (dissolved oxygen) becomes. I take my daughter fishing for our catfish. Anything smaller than five pounds goes in the tank, where they grow until they become dinner. Anything bigger is dinner! Other types of fish that work well are tilapia (in warmer climates), bream, and crappie. In colder climates, you are better off using perch, salmon, or trout. I supplement red wiggler earth worms as feed every so often, but mostly I use 30% protein fish food at the rate of one handful once a day.

The Build

In this section, I will describe my set up and the “why” behind it. You could modify this to work any way for yourself, small scale or large. I started by digging a trench 30 feet long and three feet deep. I buried a piece of black 4-inch drain pipe without the holes, leaving one end sticking out of the ground, which is outside of my greenhouse and has a screen filter on it. The other end comes up inside the greenhouse. A small 4-inch fan pulls outside air in, cooling/warming it (depending on time of year) using geothermal energy as it passes through the pipe. This also creates a positive pressure inside my greenhouse. I built a PVC-framed greenhouse covered with Polyethylene. The greenhouse is closed at one end and has a door at the other. I use a 60% shade/filter over the top during the heat of summer. This allows the greenhouse to stay cool in the summer. I use an IBC tank, which holds about 150-170 gallons. I cut the top off and flipped it over to hold the expanded shale. On the surface of the expanded shale is where the two types of bacteria convert ammonia to nitrates.  The lower part of the IBC is buried to ground level. By doing this, the water stays close to ground temp, which eliminates my need for a water heat source. The top is covered with a *dark blue tarp to keep light from getting in. Any place light can touch the water will cause algae to grow. I have a 400 gph pump that pumps water constantly up to a dark blue, 40-gallon plastic drum through a swirl filter; the bottom of the two 40-gallon drums sit about three feet off the ground. This is the first step that removes solids. This must be the first step, because those solids WILL clog up the grow bed media (thus causing “dead spots”). That water then flows to a second ibblue drum bio filter. Look at YouTube for designs on both. When the water leaves the blue drums it overflows into the 4″ pvc NFT system. The NFT tubes consist of (6) 4″ PVC pipes that are 10 feet long,  interconnected so that water flows in at one end and out the other, passing along the roots of 70 plants along the way. I plant 15 plants per week in small trays. (See the section on “Seeding and Trays” below). The lettuce is 68-day Butterhead Bibb lettuce and spends the last four weeks growing in the NFT. I prefer Bibb as it has thicker leaves, a buttery taste, and is often considered gourmet lettuce. I have the pipes over the expanded shale to shade it from getting hot. If your grow media, like gravel or shale, gets too hot, it will warm up the water and kill the fish. You must shade it somehow, either with vegetation or another means. From the PVC NFT system, the water has a constant inflow into the shale. Once the water level fills to just below the surface (about 1″), a 1″ PVC bell siphon kicks in and drains the tank. This is also a crucial part of my set up because it drains about 18 Gallons of water in three minutes. This quick rush of water draining back into the fish tank keeps the water stirred and aerated, thus eliminating the need for an air stone. Because so much water enters with such force, it breaks the surface tension of the water, allowing CO2 and other harmful gasses to escape and not suffocate the fish. Then the water is pumped back to the blue drums and thus circulated. The only power required for this is my 400gph pump and 4″ fan for the greenhouse. In the event of a power outage (short or long term), I have planned to keep the system running with minimal input. Ahead of time, I’ve installed a 1/4″ drain pipe on the bottom of the second blue drum with a flow regulator. If the power fails, I’ll have to go out twice a day and manually use a bucket to fill the 40-gallon drum from the reservoir. From there, gravity will force water through the NFT system, and the bell siphon will drain the upper tank. The only power necessary to keep the whole thing running is for the 4″ air fan.

Seeds and Start Up Trays

I use only pelleted heirloom seeds, when possible. I prefer to buy 2,000-10,000 seeds at a time and keep them in the freezer. I have two grow trays that I keep in the garage. I use Rockwool 1.5″ starter blocks. Rockwool tends to be caustic, meaning it has a pH of 8.0. An ideal range for any aquaponics system is 6.3-6.6. If you don’t lower the pH of the Rockwool ahead of time, the seeds generally will not sprout. Before planting I soak/submerge the Rockwool in a bucket with water and squeeze a lemon into the water, mixing it before putting the cubes in. I let them sit for 12 hours, thus lowering the pH to around 6.0-6.3. I then take them and put them into a tray, insert one pelleted seed per cube, and put the lid on the tray. Usually seeds will sprout in 10 days. Once the second set of leaves appears, I transfer the sprouted cubes to a second tray. I keep the water in the bottom of the slotted sprouting tray at as little as possible, just barely touching the rock wool. The cubes will soak up water, thus causing the roots to shoot out the bottom. Once the plant is about 35-40 days old, and root development is long enough, I transplant them to the NFT PVC pipes. Spacing at this point is 8″ apart.

Pests and Pest Controls

Anyone who does this for any amount of time will find that once pests arrive, they’re hard to get rid of. I keep ladybugs and predatory wasps in my greenhouse year round. A ladybug will eat 50 aphids per day and predatory wasps usually take care of the rest. They seek out and find aphids and other pests. If an outbreak is too bad, I will apply organic controls using a spray bottle and spraying directly on the leaves. Usually a citrus and castor oil blend will do the trick. Make sure not to get it into the water, as fish are usually affected quite easily. 

In Closing

The best part about aquaponics is that once the system is all set up, there is very little upkeep. I haven’t had to weed in two years. It’s wonderful! You’ll also find that the nutrition levels of your aquaponic lettuces, fruits, and veggies are higher than store bought by leaps and bounds, not to mention that it always tastes better when you grow it yourself. I’ve killed all of my fish three different times. I add 10 gallons of water per week to keep the tank topped off. In a SHTF scenario, fresh lettuce and herbs provide lots of flavors and roughage. In stressful situations, the last thing you want is a GI block or GI problems after all of the preparation. Add this in with fresh fish, crawdads, beans and rice, rice and beans, and life shouldn’t take too much of a hiccup. God bless all of you, and stay vigilant! Work like it all depends on you, and pray like it all depends on HIM!!! 

Proverbs 22:3