It's been just over 5 years since we started our aquaponics project. In retrospect, I'm glad we did it but I'm not honestly sure of it's value in a sustainable system. These are the challenges I've struggled with over the time we've had the system.
The first issue has to do with fish feed. This one is slowly being resolved but the solution is expensive. When we first started there was no organic fish feed. And, there is no way you can "grow" your own fish feed for an intensive system such as an aquaponics system. The food that was available was commercial and I am certain full of GMO products. For some folks, this is fine. They trust the safety of these products. I, unfortunately, am not one of those people. The fish grew fine and the system worked, but my conscience has bothered me for a long time. Now there is organic fish feed available, though the cost is significantly higher.
Temperature / Electricity
We chose to grow tilapia as they were supposed to grow to full eating size in one year. They can take a lot of water variation and seem to do well in intensive systems. Unfortunately, they do not grow as fast in a temperate area unless you want to add a lot of heat to the system. We chose to take a minimal approach and aim for around 60-65 degrees F in the winter. That meant the fish survived but did not grown for 4-5 months out of the year here. It took two years to get fish up to a good eating size. And, the electricity bills were pretty substantial in spite of the steps we took to winterize the system.
We are in the Pacific Northwest area of the United States. We have very low light in the winter due to the number of days with cloud cover. Plants don't grow well without sufficient sunlight. What we learned was to have plants "grown" out going into winter. That means having vegetables ready to eat. The ones who could tolerate the cooler temperatures and high humidity did well and it was somewhat like having food in refrigeration just waiting for us to eat it. Surprisingly, our San Marzano sauce tomato has provided us tomatoes up until Christmas. By January is has been pretty bleak in the system and by mid February we have been able to plant salad and start the season again. I have taken advantage of the limited system plant growth in January and February to setup lights and a heating pad to start seedlings for the garden.
We pulled the last of the tilapia last fall and have let the system just run with no heat or plants over the winter. With spring, I feel the itch to get plants growing in there again. We've looked at what kind of fish would do well in our system. The water temperature this winter got down to around 40 when it was cold, though we had a fairly mild winter. And, it gets up into the low 80's in the summer time. The only edible fish we've found to survive those kinds of temperature fluctuations are blue gill. The other option is to grow something ornamental like koi or comets. We're still undecided.
Plants we've grown successfully:
- Cucumbers - we've grown Telegraph greenhouse cucumbers for several years now. They start growing in March and we have wonderful long cucumbers by early summer. The plants suffer in the heat but we are able to get a second round in the fall before the cool temperature and humidity kill off the plants.
- Peppers - love the heat in the summer system. When we were heating the greenhouse in the winter we could actually overwinter the plants. As soon as the light got stronger, they plant would start to produce flowers and there would be peppers all summer long into the fall. This last winter, the plant didn't make it. If we wanted peppers again, we could start them early under lights and have them in the system now (mid-March) growing well.
- Tomatoes - Same story as the peppers. They love the heat and overwintered with some heat in the greenhouse.
- Ginger - I harvested a large strainer of ginger this winter from one large piece planted last spring.
- Basil - another heat lover, does great all summer. Basil does seem to be sensitive to the quality of light and there's a point in the fall where it just all dies regardless of temperatures.
- Salad greens grow well in the spring and the fall. The humidity in the heated greenhouse in winter didn't work well for greens. I would think next winter, we could overwinter all kinds of salad greens with no heat in the system.
- Brassicas - I think these would do well in the system over winter with no heat. We were only able to get cabbage to do well with the winter heating.
Thoughts on aquaponics and sustainability
Since we first started this project, I've learned a lot about permaculture and other forms of gardening. As you may have seen in other parts of the site, we've also planted a food forest on our small suburban lot. I believe the greenhouse would better serve us as a home to overwinter vegetables and start plants for the outdoor garden. The summer heat could still be used for the heat lovers that have so enjoyed the aquaponics system. We also have a pond where we could grow some blue gill or perhaps perch, Though we would not be able to grow fish intensively, we'd be using a lot less in the way of inputs into the system. Its a great idea to consider aquaponics as a closed system, but its really not. You have to feed all those fish.