Several definitions of aquaponics acknowledge the presence of “ponics,” which pertains to the hydroponics aspect of growing plants in water without soil using a medium. Hydroponics is a distinct method of cultivation with its own advantages and disadvantages, which will be discussed further on.
Aquaponics is essentially utilizing fish for a productive purpose. Specifically, the activities carried out by these fish (eating and producing waste) serve as an ideal fertilizer for plant cultivation. Remarkably, when fish are employed in this manner, they have the capacity to promote substantial plant growth.
Aquaponics is remarkable because it replicates a natural ecosystem, showing the interconnectedness of water, aquatic life, bacteria, nutrient dynamics, and plants that coexist in waterways worldwide. By following the principles observed in nature, aquaponics effectively combines these elements together. Specifically, it utilizes the fish waste as a food source for bacteria, allowing them to convert it into an ideal fertilizer for the plants. The plants then purify the water, making it safe for the fish, just as nature does in any aquatic ecosystem.
Aquaponics takes advantage of the benefits and eliminates the drawbacks of both aquaculture and hydroponic systems by merging them together.
Let’s analyze the alternative methods of cultivating plants and fish and assess their comparison with aquaponics.
Traditional Soil Gardening
When attempting to grow plants, the management of soil can either be a time-consuming task or a valuable natural resource.
- Some soils have robust fertile live soil-web ecosystems. However many soil structures that are heavy in clay or sand have challenges related to water, nutrient availability, and texture for planting. Many locations lack soil access because they have concrete, asphalt, or rock to contend with.
- Along with water runoff, erosion, wind, and other soil-depleting events, soil loses fertility with each crop. To grow plants in soil, it is necessary to reapply compost or some other fertilizer each growing season. Fertilizers with only N – P – K (Nitrogen, Phosphorus, and Potassium), means that the plants grown will absorb these nutrients, but could be depleted of other micro-nutrients such as calcium, boron, copper, iron, zinc, and many others. Applying too much synthetic fertilizer or uncomposted manure can create salinity issues rendering the soil “too hot” to grow crops.
- Managing weeds, pests, insects and diseases takes a significant amount of the gardener or farmer’s time. Weeds crowd plants, taking water and nutrients, not to mention all the time wasted killing or pulling them out. Pesticides, herbicides, and other chemicals can also kill precious soil microbes and can be dangerous to bees, butterflies, birds, other animals, and humans.
- In large-scale industrial farming, agrochemicals (fertilizers, pesticides, and herbicides) along with Genetically Modified Organisms (GMOs) are of concern when choosing vegetables, fruits, and herbs. Organically grown crops do not allow GMOs but do have a wide variety of products used for pesticides.
- Soil can be very difficult to water correctly. Overwatering can result in flooding, evaporation, runoff, and soil compaction, prevent air from getting to the roots and kill plants with saturation. Alternatively, too little water, hot dry climates, drought, and water shortages can wreak havoc on plant growth and can easily result in plant death as well.
- Gardening can be an enjoyable past-time but also demands a certain amount of digging, bending, and physical labor
- While gardens can be located in your backyard. Industrial farms are often thousands of miles from where their food is consumed. This requires extensive transportation, refrigeration, and packaging to get the food from farm to table.
Traditional Hydroponics
Although hydroponics is effective in solving numerous soil-related problems, it also presents its own set of issues.
- Traditional hydroponic systems rely on the careful application of expensive, man-made nutrients made by mixing together a concoction of chemicals, salts, and trace elements. In aquaponics, you merely feed your fish inexpensive fish feed, food scraps, and food you grow yourself.
- The strength of this hydroponic mixture needs to be carefully monitored, along with pH and total dissolved solids (TDS). In aquaponics, you carefully monitor your system during the first month, but once your system is established you only need to check pH and ammonia levels weekly or if your plants or fish seem stressed.
- Water in hydroponic systems needs to be discharged periodically, as the salts and chemicals build up in the water, becoming toxic to the plants. This is both inconvenient and problematic as the disposal location of this wastewater needs to be carefully considered. In aquaponics, you do not need to replace your water; you only top it off as it evaporates.
- Hydroponic systems are prone to a disease called “Pythium” or root rot. This disease is virtually non-existent in aquaponics.
Recirculating Aquaculture
The majority of mainland fisheries consist of Recirculating Aquaculture Systems, also known as RAS, which aim to filter and recycle water in fish tanks. Although RAS endeavors to tackle water conservation, it also presents its own set of problems.
- The tank water becomes polluted with fish effluent, giving off high concentrations of ammonia. Water has to be discharged at a rate of 10-20% of the total volume in the tank daily. This uses a tremendous amount of water. Again, in an aquaponics system, you never need to discharge your water
- This water is often pumped into open streams where it pollutes and destroys waterways.
- Because of this unhealthy environment, fish are prone to disease and are often treated with medicines, including antibiotics. Fish disease is rare in an aquaponics system.
Aquaponics
Aquaponics is a game changer as it combines the benefits of various growing techniques, mimicking a natural ecosystem by utilizing waste from one element to benefit another.
- Waist-high aquaponic gardening eliminates weeds, back strain, and small animal access to your garden.
- Aquaponics relies on the recycling of nutrient-rich water continuously. In aquaponics, there is no toxic run-off from either hydroponics or aquaculture.
- Aquaponics uses 1/10th of the water of soil-based gardening and even less water than hydroponics or recirculating aquaculture.
- No harmful petrochemicals, pesticides, or herbicides can be used. It’s a natural ecosystem.
- Gardening chores are cut down dramatically or eliminated. The aquaponics grower is able to focus on the enjoyable tasks of feeding the fish and tending to and harvesting the plants.
- Aquaponic systems can be put anywhere, use them outside, in a greenhouse, in your basement, or in your living room. By using grow-lighting, space can become a productive garden.
- Aquaponic systems are scalable. They can fit most sizes and budgets, from small countertop herb systems to backyard gardens, to full-scale farms, aquaponics can do it all.
- And the best part – You get to harvest both plants and fish from your garden. Truly raising your entire meal in your backyard.
- Instead of using dirt or toxic chemical solutions to grow plants, aquaponics uses highly nutritious fish effluent that contains all the required nutrients for optimum plant growth. Instead of discharging water, aquaponics uses the plants, naturally occurring bacteria, and the media in which they grow to clean and purify the water, after which it is returned to the fish tank. This water can be reused indefinitely and will only need to be topped off when it is lost through transpiration from the plants and evaporation.
Farming on a Loop
Aquaponics is being increasingly acknowledged in Hawai?i and the Pacific, as well as globally, for its ability to generate high yields while minimizing waste and cost. This is particularly valuable due to the limited physical space available for agriculture in this region compared to continental landmasses. Therefore, the combination of efficiency and minimal impact on land and water use offered by aquaponics makes it a highly practical method for food production in the Pacific area.
Aquaponics involves combining aquaculture and hydroponics, creating a farming process that operates in a continuous loop. In this system, fish or shellfish are raised in tanks or ponds, while plants are grown in water. The waste produced by the animals serves as a nitrogen-rich fertilizer for the crops. In closed systems, the water is circulated in a cycle, providing nourishment for both animals and plants.
The method has been practiced for a long time, and there is evidence of its early use in East Asia and Mesoamerican civilizations many centuries ago. Initially, aquaponics involved using raft systems where plants floated on top of water containing fish. This approach is still employed today. However, modern aquaponics has evolved and become more customized, thanks to human creativity and advancements in technology.
All variations of the system have the same fundamental components, including water, light for the plants, feed for the fish, bacteria responsible for converting fish waste into chemicals usable by the plants, and an electric pump used to circulate water in the system, ensuring it remains well-oxygenated.
The results, usually consisting of leafy greens like spinach or kohlrabi, as well as fish like tilapia or catfish, are impressive. Typically, this method yields more fish and crops using less water and feed compared to separate farming and aquaculture. In the case of catfish-pumpkin systems, aquaponics can enhance fish production efficiency by up to 75 percent compared to other aquaculture methods, and it can increase pumpkin yields five times more than growing the crop in irrigated soil.
Aquaponics is becoming more and more appealing in Hawai‘i due to its scalability, ranging from large-scale farms to small backyard units, and its low operating cost. This makes it an ideal solution for addressing the ongoing issue of food insecurity. Aquaponics is being recognized for its ability to provide healthy food at various scales and improve overall crop and aquaculture efficiency. The collaboration between federal and local governments, educational institutions, and nonprofit organizations is now promoting the training and adoption of aquaponic techniques in Hawai?i and Pacific communities.
Planting the seeds, teaching the fundamentals
GoFish Hawai?i is a workshop series on aquaponics principles, held in collaboration with the University of Hawai?i College of Tropical Agriculture and Human Resources (CTAHR) and the University of Hawai?i Sea Grant College Program (Hawai?i Sea Grant). The workshops take place at CTAHR’s Waim?nalo Research Station and aim to provide training on aquaponics.
According to Dr. Kai Fox, a coordinator for GoFish and an extension specialist for Hawai’i Sea Grant, the workshop series currently has approximately 35 students attending at once, and he observes an increasing need for training.
According to Fox, a significant portion of the interest lies in incorporating a new source of nutrient water into your farm rather than completely reinventing it. He further explains that the workshop’s approach primarily focuses on familiarizing students with the technology and allowing them to independently explore it.
According to Fox, a small number of students have decided to continue their involvement in the workshop series by participating in a practicum. The practicum focuses on a “decoupled” aquaponics system, which involves using water from tilapia culture to regularly water a mixed avocado and citrus orchard that covers a quarter-acre. This system is beneficial as it helps recycle nutrients from the pellets used to feed the fish.
Aquaponics training is being implemented in some high schools. Wai?anae High School, located on the leeward side of O?ahu, offers aquaponics principles as part of their aquaculture program at the Marine Science Learning Center. This program has been active since the early 1990s. Students at the center gain hands-on experience in aquaculture, which helps them understand sustainability and ecological concepts. Katie Kealoha, who co-runs the center with marine science coordinator Dana Hoppe, mentions that students can design systems resembling aquaponics to handle the waste produced when cultivating saltwater fish and algae.
Hoppe mentions that they consistently make an effort to help the children comprehend concepts related to food security, food systems, and their influences. This is especially important because their community is located in a food desert. Hoppe explains that the aim is for the principles taught in the program to be understood and implemented by students in various contexts beyond aquaculture.
A newfound and enthusiastic demand
Aquaponics is experiencing growth across the Pacific. In January 2020, the Guam Green Growth Initiative (G3) teamed up with an AmeriCorps VETCORPS team and the University of Guam (UOG) Sea Grant to establish a community garden in Talo?fo?fo. The garden features an aquaponic system that incorporates the recycling of white goods such as appliances, freezers, and refrigerators. David Crisostomo, an aquaculture specialist supported by Hawai?i Sea Grant and UOG Sea Grant, describes the system as a small-scale, backyard, family-use setup.
Crisostomo mentions that there are additional systems scheduled for implementation in various communities throughout the island.
Crisostomo explains that they are approaching it with the notion of taking small steps before taking big steps. They want to begin the community by providing something that is reasonably priced and advantageous for the people to support their families. This might result in producing surplus that can be traded with other farmers.
