The Science of Aquaponics
The biology behind an efficient and environmentally friendly technique for farming fresh, nutritious food
Aquaculture, hydroponics and aquaponics are all farming practices that have become increasingly popular in recent decades (although some of them have been used by humankind for millennia). Together, these farming techniques comprise the new wave of agriculture, which is one that is more holistic, natural, and efficient in its approach to growing food. But what’s the difference between them and, more importantly, how can an agricultural system that leverages the power of these methodologies help to address the food crisis here in Puerto Rico and in other communities around the world facing economic, climatic, and environmental hardship? Let’s take a closer look….
Aquaculture is the farming of fish, typically in a contained environment that is closed off to external influences and where variables like temperature, oxygen, and water quality are controlled. Hydroponics is the farming of plants whose roots are submerged in a continuous flow of nutrient-rich water, also in a closed, contained, climate controlled environment. Aquaponics is the fusion of these two farming techniques: aquaculture + hydroponics = aquaponics.
How does an aquaponics system work?
The concept is simple. Fish are farmed in large tanks. As the fish are fed, they poop, and the water gradually becomes filled with their ammonia-rich wastes. Normally, the fish tanks are regulated by biological filters that neutralize ammonia and other waste chemicals. In an aquaponics system, however, this ammonia-rich water is piped out of the tanks and circulated around the hydroponics portion of the farm.
The hydroponics section consists of vertically stacked grow beds of vegetables and herbs whose roots are suspended in the fertile fish water (i.e. no soil is used). Bacteria in the root systems of the plants break the ammonia down into nitrates, which is excellent fertilizer. They then absorb the dissolved nutrients in the water, eliminating most of the ammonia, which, in high levels, is highly toxic to the fish. The naturally filtered and cleaned water is then returned to the fish tanks, ready for its next load of “fertilizer.”
Natural bacteria residing in the water, the roots of the plants, and in the guts of the fish work together to establish a balanced ecosystem where both fish and plants don’t only survive but thrive. And, after about six months, the mini-ecosystem formed by an aquaponics setup will begin to show signs of high-level, self-regulation. So you see, aquaponics leverages the natural relationship between plants and fish: the fish providing food for the plants and the plants removing the fish’s waste products from the water, which can then be returned to the fish tanks as you can see in the diagram below.
The Nitrification Process
The “nitrification process” that occurs in an aquaponics system is a two step process that mirrors what happens in natural water ecosystems. As soon as the ammonia-rich wastes of fish enter a water stream, the natural “good” bacteria in that water begin to complete nitrification of the ammonia; in other words, transform the ammonia, which is an organic chemical compound, into nitrates, which are powerful plant fertilizers (also organic chemical compounds).
As the above diagram shows, the first step show Nitrosomonas bacteria converting the ammonia into nitrites, not to be confused with nitrates, the desirable end product. Then, Nitrospira bacteria convert the nitrites to nitrates and it is the latter organic compounds that are absorbed by the plants. The nitrification process occurs in the open water before absorption by the plants.
At Fusion Farms, we employ a “swirl filter” which is where the bioactivation occurs after most of the larger fish sediments have settled to the bottom of the tank and have been filtered out of the system. Then, instead of just disposing of this waste stream like most aquaculture operators do, we run it through a super-oxygenation and hyper activation process in a separate tank for up to six months in order to extract all of the ammonia, breaking the fish sediment down into suspended molecules that can be used to fertilize our plants.
This is exactly what occurs in most natural environments, like the bottom of a pond, lake, or river, where the murky silt at the bottom of the water is incredibly rich, fertile, and bursting with nutrients for plant growth.
The Difference between Aquaponics and Traditional Land Farming
The benefits of aquaponics are numerous, particularly in the context of Puerto Rico, which currently imports upwards of 90% of its fresh food. For starters, it minimizes the impact of external conditions on a harvest, which means that, come rain, shine, or even hurricane, the plants and fish being grown will continue thriving. This is very much unlike traditional land farming, which is directly exposed and vulnerable to the weather and other external influences like molds, pests, fungi, and even hungry animals and birds.
Here are more benefits of aquaponics compared with traditional land farming:
- Vastly reduced water consumption: The constant cycling of water in an aquaponics facility reduces the water demands of a farm by 90% compared with traditional farming operations. Here at Fusion Farms, we have also installed enormous rainwater tanks, which almost entirely eliminate our reliance on Puerto Rico’s municipal water, while our solar panel installation, battery backup, and generators supply our farm with the vast majority, if not all, of the electricity we need to power our operations.
- Improved plant density: In an open field, plants develop large root systems to access the water and nutrients they need to grow and so they need to be placed further apart, which requires large tracts of land. Additionally, growth energy is expended on the development of larger root systems rather than the edible parts of the plant, such as the stems, leaves, and flowers. In an aquaponic system, however, the plant’s roots are suspended in nutrient-rich water, which means that (1) they can be placed much closer together because they don’t develop large root systems and (2) most of the energy is concentrated on developing plant density. Consequently, aquaponically grown plants are incredibly lush, dense, and nutritious and as much as six times less space is required to grow to same yield as traditional agriculture.
- 24/7/365 Plant production: Within our facility, we establish a natural cycle that fuels plant growth and delivers seed-to-harvest produce in as little as 21 days. Additionally, our carousel grow cycle means that we can grow 24 hours a day, 365 days a year with consistent output unlike traditional farming, where plant growth only takes place during daylight hours and within seasonal cycles.
- Fresh, local produce in any climate: Because aquaponically grown plants do not require soil, they can be established indoors in locations that have hot and dry or cold, severe climates or in locations with nutrient-leached sandy soils. In fact, there are no limits on where aquaponics facilities can be established, even in hurricane zones like Puerto Rico. All you need is the right investment and a team of people passionate about providing communities with hyper-local, sustainable, and healthy food.
- Pesticide, fungicide, and additive free: The food grown in aquaponics systems is protected from molds, fungi, diseases, and pathogens and so no harmful, chemical additives are required to control them. Similarly, the fish tanks are closed to external influences and so we don’t have to treat them with antibiotics or any other chemicals, which makes them a clean, healthy, and delicious source of protein.
Traditional Land Farming Versus Hydroponics and Aquaponics
|Traditional Land Farming||Hydroponics||Aquaponics|
|Water use||Daily irrigation of large tracts of land = huge water bill.||Requires less water than traditional agriculture because much less land is needed to produce the same yield. Also, the water is circulated throughout the system, retaining it.||Similar to hydroponics, aquaponics recycles the water in the system, only requiring 10% of the water used by traditional agriculture.|
|Land use||Traditional farming requires large tracts of land. Every plant you put into the ground occupies a fixed space that doesn’t change throughout the maturation period of the plant.||Hydroponics requires 15% of the land to produce the same yield as traditional agriculture.||Similarly, aquaponics requires 15% of the land to produce the same yield as traditional agriculture.|
|Nutrient source||Animal manure||Chemical fertilizers||Fish poop|
|Carbon footprint||Traditional farms have a huge carbon footprint. Not only do they require daily work by heavy machinery that guzzles gasoline, they are also located hundreds, even thousands of miles away from their intended markets or distribution channels, requiring expensive transportation and food miles.||Hydroponics greenhouses can be built in locations that are closer to their intended markets or distribution channels, which greatly reduces carbon footprint. Also, no fossil fuelled tractors or heavy machinery are required.||Similarly, aquaponics setups are hyper local, which greatly reduces carbon footprint. They don’t require heavy machinery to operate and oftentimes, incorporate renewable energy sources like solar and wind.|
|Yield per acre||Low: plants develop large root systems to access water and nutrients and so they need to be grown far apart in order to flourish. This takes up large tracts of land for a smaller food output.||High: with the plant’s roots suspended in nutrient-rich water, the roots systems remain small but the plant grows densely. As such, they can be stacked close together and, using vertical rack systems, one on top of the other for a yield that can be six times per square foot than that of traditional agriculture||High: similarly, using deep water rafts filled with nutrient-rich fish water and vertical rack systems, aquaponic farming can grow six times the amount of produce per square foot than traditional farming.|
|Pest control and bio-security||Required: being exposed to the environment and external factors like molds, fungi, pests, and even hungry birds and animals, traditional land farming requires pest control such as pesticides, fungicides, and other nasty chemicals. Produce may be exposed to harmful pathogens.||Not required: hydroponics systems are kept in closed systems, protecting them from pests and the need to use harmful chemicals. The produce is also much cleaner and free from harmful pathogens.||Not required: similarly, aquaponics systems are closed to external influences, negating the need for pesticides and other chemical additives. The produce is also much cleaner and free from harmful pathogens.|
|Start-up costs||Traditional farms require large tracts of land, heavy machinery to operate, and enormous labor, water, fertilizer, and power costs to run.||Start-up costs are much lower than with traditional farming. Hydroponics farming systems are easy to build, simple to maintain, and affordable to keep up.||Similar to hydroponics with the additional cost of purchasing and maintaining fish tanks, although the fish feed the plants so you save on purchasing plant fertilizers.|
|Maintenance||In typical farms, massive volumes of water, fertilizers, pesticides, and chemicals must be used. They require daily irrigation and regular fertilizing and pest control. In other words, they require a lot of maintenance and hard work.||Require water and fertilizer throughout the entire growing season but this is often automated and so, other than monitoring and harvesting, little work is required to maintain hydroponics systems.||Aquaponics systems eventually establish a high-level of self-regulation. The only maintenance work required is daily monitoring of climatic and water variables and occasional cleaning and harvesting.|
In short, Fusion Farms’ aquaponics system can operate independently of the environment, the weather, the seasons, and the island’s wavering infrastructure, supplying Puerto Rico with a reliable source of fresh, nutrient-rich leafy greens, herbs, vegetables, and fish. With time, we plan to diversify our produce, adding fruit trees and all kinds of delicious vegetables to our harvests.