My skeptical mother fretted as my father and I began digging a huge hole in our backyard in the Fall of 2010. After sketching out a design for a 12 x 12 x 16 x 16 greenhouse with a 45 degree slope facing roughly south and two internal 4 x 4 x 8 foot fish ponds, we began to dig. But the rains came, and the ponds filled with water, and stayed full of water, until we pumped them out, and then they filled again. It wasn’t until the Spring of 2011 that we could begin framing in the greenhouse and ponds.
At about two and a half feet down, we hit bedrock, and progress was slow. Having carefully calculated that two 4 x 4 x 8 foot ponds would comfortably accommodate at least 300 fish, we dug deeply enough to created two 4 foot deep ponds.
We lined our ponds first with HardieBacker cement board and then with styrofoam in order to maximize heat retention. After spending ample time making sure our foundation was square, we built a basic 12 x 16 foot perimeter for our greenhouse. We continued by cementing supportive posts into the ground at the corner of every four-foot square of the greenhouse and around the perimeter . Once we finished cementing our posts into the ground, we bolted 18 foot 2 x 6′s to the posts at 45 degree angles.
Next, we began the process of lining the ponds. First we lined the entire surface area of the ponds with black felt in order to minimize the risk of any splinter piercing the pond liner . After adding extra cushioning to particularly hazardous places like sharp corners, we lined our ponds with sturdy 45mm EPDM pond liner.
Our growbeds came next. We constructed two 1 x 2 x 5.5 foot growbeds and two 1.5 x 2 x 5.5 foot growbeds for plants with relatively shallow or deeper root systems, respectively. In the bottom of each of our growbeds we drilled a small 7/8 inch hole for drainage. As with the ponds, we covered these growbeds with black felt, followed by 45mm pond liner. Using an X-acto knife, we made a small cruciate in the lining of each of the growbeds directly above the hole we had drilled in the wood beneath, careful not to make too large of an incision. We plugged these holes with plastic drain replacements, and sealed the area with waterproof silicone sealant. In addition to the felt and pond liner, we lined the growbeds with a water-permeable weed-blocker fabric in order to prevent our siphons from getting clogged. With a couple feet of vinyl tubing, we attached a loop siphon to each drain. We also added emergency backup drains near the top of each of the growbeds in order to prevent them from overflowing in the unlikely case that a siphon fails.
Having finished the basic frame for our greenhouse, we moved on to completing the exterior. We covered the greenhouse with 8mm twin-walled UV-coated polycarbonate panels, which are designed to maximize both light exposure and heat retention while filtering out as much harmful radiation as possible.
At the top of one of our polycarbonate panels, we removed a 3 x 4 foot cross section and attached it to a solar-powered vent opener. On particularly sunny days, this vent will prevent the temperature in the greenhouse from climbing up to 150 degrees, as it did one day before we had installed this vent.
After completing the structure of the greenhouse itself, we filled our growbeds with hydroton clay pellets that were donated by our good friend Mr. Louie and filled our ponds with water. We planted tomatoes, snow peas, basil, beets, and a number of other crops in our growbeds, and added a couple goldfish to each pond. Goldfish are extremely tolerant fish, and it is a good idea to add a few of them to any new pond you wish to fill with some other species of fish, as they will help to acclimate the water. We purchased four pumps–one for each of our growbeds–and placed two in each pond. This way, each pond will have its water constantly filtered even if one pump malfunctions.
This process of building the greenhouse itself took about half a year. In the meantime, we were raising a number of small fry and fingerlings in our garage in a small 40 gallon tank with a Fluval filter. Many young fish are better kept indoors in heated, filtered water until they are several weeks old. At one point during the summer, my father and I took a week to visit colleges on the East Coast. Three days in, we received notice that our fish–in the care of my younger brothers–had all died. Fortunately, a new order of seventy-five arrived at our door before my father and I even did, and a second order arrived in the beginning of fall. These one hundred and fifty fish are alive and well and are living outside in our greenhouse today.
The great thing about setting up an aquaponic system is that after the initial construction, it can be complete — or, it can never be done at all. Besides the occasional need to drop some food in the water and harvest some wild vegetables, our system is basically self-sustaining. However, my father and I have found that keeping our hands off a project that we have spent so many hundreds of hours working on is not easy. We’re always adding, experimenting, altering, learning. After finishing the greenhouse we built a couple of thermosiphons that will help naturally heat the water in our ponds. We built a deck around the greenhouse. We constructed tanks in which to grow duckweed to feed our fish. We built an outdoor solar shower. There are always new things to try. What vegetables will grow best? How much will the type of food you give your fish affect their taste and nutritional quality? Will growing different species of fish together prove beneficial or counterproductive? Aquaponic systems can always be improved.
So maybe you are one of those people who can construct an aquaponic system and leave it to itself. But don’t say I didn’t warn you. If you start to build one, there’s a very good chance you’ll never stop.