This summer I built an aquaponic garden in my backyard. It is my second season, or third if you count the indoor garden I built indoors for the tilapia when the weather got cold last fall. It is an ecosystem, like a bog and a bay, supporting life on many levels. I quickly come to love this form of gardening more than any other. And I have taken a leap of faith, deciding to turn my new passion into a business. I have been learning all that I can, reading publications, and watching videos at the “Youniversity of Tube” and by experiment. It is now clear to me that once your passion can become your job then your life becomes filled with joy.
Aquaponics utilizes fish and their waste produced as the nutrient source for growing plants. Plant beds and the naturally developing biofilm of microorganisms convert ammonia to nitrogen, which provides nutrients for the plants while removing the toxic ammonia from the water; this is equivalent to as naturally occurring bog or biological filter for the fish. What is as exciting as the fish, herbs and vegetables produced is that there are many ecosystems occurring in an aquaponic garden. In a controlled environment they are as fun to watch as any aquarium or terrarium might be.
Among the backyard aquaponic systems that have been shared through upload to YouTube, most are ebb and flow designs. They water from the fish tank floods floods the soil-less rock beds and drains back to the fish tank throughout the day. Like others, this cycle repeats every hour for 15 minutes, though a frequency of 2-4 times per day is adequate for most plants. Ebb and flow is nice for several reasons: the rock medium supports a large root system, it requires little energy to run a low volume pump on a periodic basis, the gravel beds are easy to work with when sowing seeds, dividing roots or propagation from clippings. The rocks also serve to filter out the solid matter from the water. Most important, the bed rocks provide a ideal habitat for bacteria to colonize and facilitate the nitrogen cycle. Because oxygen is drawn in and out with every bog-like flood cycle, ebb and flow rock beds may be seen as the lungs of the design, hosting an environment for aerobic bacteria to convert ammonia to nitrogen, replenishing oxygen needed for the plants and helping to oxidize waste, and it provides support for large plant root growth.
This year, I am experimenting with deep water designs. It is a hydroponics technique more often used with lettuce, basil and herbs. In this setup, water is continuously moving under floating rafts that allow the plant roots to spread freely, trapping and filtering nutrient rich water as it passes through. While there are more symbiotic relationships established than one could imagine, I have enjoyed the simple genius of few. In Most continuous flow water culture utilize clarifiers, degassers and other mechanical elements to separate out fish solids. That is one effective approach that allows the waste to be recycled through vermiculture and other methods of compost. I have found that allowing the waste to remain and by introducing bog plants, supports more ecosystems that add biodiversity to the entire garden.
There are damselflies that morph from the water in the early morning. The nymphs or naiads crawl from the water during the night and become flying damsels as they shed their skin, leaving behind only the form of their transitional bodies along the walls of the bed. They hover about, dancing in the air, in a joyful display of affection for their environment. Damselfly nymphs in the water play their own roles in this ecosystem, living on leaves of aquatic plants, feeding off of baby fish and aquatic insects. Their predators include larger aquatic insects and fish. Damselflies themselves are considered beneficial garden insects as they prey on fruit flies, mosquitoes and gnats. Considering all the rain we’ve had this summer, and that they consume up to 10 mosquitoes per day, their presence brings a smile. From personal experience I can testify, the simple act of watching this take place has a positive impact on the sense of well being.
Anacharis is an aquatic plant that not only supports the damselfly life cycle; but after the tilapia eggs hatched and the fish fry appeared, I noticed the babies spend time hiding out among these plants. Evidently this is not only for protection from predators, but also they are feeding on protozoan’s that inhabit the same area. Anachris stays completely immersed in water, producing underwater oxygen on its leaves during photosynthesis. An oxygen environment supports aerobic bacteria, which feeds the protozoan. These serves as a primary food for the fry. This ecosystem is one that is proving to be valuable, as raising baby fish can be a delicate process. Without any effort, the bog environment provides for itself, making an ideal habitat for raising fish.
Another unexpected eco-phenomenon is the presence of honey bees. In the past few years there have been very few. Today they settle on the floating duckweed that grows on the waters surface. They come one by one and two by two, every 10 or 15 seconds, from morning till early evening. Evidently the bog flavored water suits them well as they have found this an oasis, to which they have directed their entire colony. This is another ecosystem that can be easily appreciated at a time when honey bees welfare is otherwise threatened. They are a reassuring sight in any fruit bearing garden.
I have recently added crawfish for their role in producing phosphorus, a nutrient that aids in the flowering of aquaponic plants. Next I may try frogs as they will eat insects and provide another cycle of life with their eggs and tadpoles.
While raising vegetables and fish in my backyard aquaponic ecosystem, I have come contributed to the rebirth of something that makes me giddy. Sometimes I feel like a child playing in a creek, discovering the nuances of life, as they unfold in a most delightful way.