By Joel Berlin
SDUN Columnist
It was thrilling to be an exhibitor this year at the San Diego County Fair as part of the Flower and Garden Show. I am always looking for the next cutting-edge product or gardening system that is green, sustainable and suitable for small, urban gardens.
I was so excited to meet Sue Spray, an expert in aquaponics, and I got the lowdown on this amazing and completely organic way to grow your own food.
Aquaponics is a crossover term, combining aquaculture (fish farming) and hydroponics (growing plants without soil). Aboriginal tribes in Australia, and the Chinese and other Asian cultures, who have combined planting crops with farming fish for centuries, understood this concept. This closed, complete ecosystem allows you to grow vegetables and fruits using nutrient-rich water from fish such as tilapia or catfish in a small space such as my balcony—which, by the way is about 3 feet by 7 feet. Crazy!
Aquaculture and hydroponics each by themselves produce significant wastewater and by-products. Combining these two into this hybrid system, the wastewater from the fish gives nutrients to the plants and the waste from the plants gives nutrients to the fish. Every avid gardener knows how fish emulation is a great way to fertilize plants. This is the same situation. An added benefit is that the bacteria clean the water and complete the closed cycle. The enriched water from the fish is gravity-fed to the planting beds. These tubs are filled with Hydroton expanded clay pellets, a soilless growing bed medium. This process continues from one tub to the next. A clever, gravity-fed vacuum flushing device—an auto siphon—empties these growing tubs into a lower reservoir, where a pump returns the water to the fish. One added plus is running the pump and air filter on a solar-operated battery. Very green! Another benefit is water conservation. Aquaponics uses one-tenth of the water of a soil-grown vegetable garden.
The Hydroton is a key component in aquaponics and is one of the best growing medium choices for anchoring plants in hydroculture setups. These highest-quality pellets—manufactured in Germany—are porous, retain moisture and transfer moisture to the roots by capillary action. They are lightweight, inert, sterile, PH neutral, contain no nutrients and are completely reusable.
For me, the big wow factor is growing my own organic protein source. For demonstration purposes, Sue set up her display using goldfish, which is an option. However, setting up the system with tilapia would provide protein for the dinner plate. Besides, how can you be sure that store-bought fish is organically grown? You would also be lowering your carbon footprint since it takes many trucks, gasoline and other products to get food to your table. It is imperative to buy healthy tilapia or catfish if you plan to harvest the fish—your search engine will provide several farms for these in the San Diego area.
Sue suggests you set up a 14-day “hospital” tank using a salt bath to kill all parasites. The bath is harmless to the fish and guarantees the system stays free of disease. The time factor to run this system is minimal—a few minutes each day to feed the fish and give your plants a look over is all it takes. I also find the sound of the running water relaxing—it’s like having your own water feature that grows food.
Sue is offering a DIY Workshop Aug. 27 and 28 at the Encinitas Community and Senior Center. Come join me and bring a few friends to learn more about aquaponic gardens.
The Urban Garden will bring you the newest technologies to green, urban gardening and landscaping. It is my hope through this series of articles that you will be inspired to look for new directions in sustainable gardening and landscaping practices. The face of San Diego is changing as water diminishes and urban sprawl continues to grow. Be inspired and make a change!
Columnist Joel Berlin owns Anandascapes in North Park.
