What are the differences between recirculating farms, hydroponics and aquaponics? And what are their environmental benefits?
Published: 10/08/18, Last updated: 6/12/23
Hydroponic and aquaponic farms are land-based systems that use recirculated, nutrient-rich water instead of soil to grow food, flowers and sometimes fish.4 6 Because they don’t require soil, they can be established in places where the soil is not suitable for farming.
Well-designed systems can also be very water efficient. Once the initial water needs (which are variable and depend on the size of the system) are met, the amount of make-up water required is minimal, because water is circulated throughout the system and is reused. Some systems use as little as 10 to 15 percent of the water required by land-based farming.7
The location and specific set up of a recirculating farm has a big impact on its energy needs; however, these systems can be efficient. Hydroponic systems established outdoors don’t require artificial lighting, and for those that are inside, energy needs can be minimized using efficient forms of lighting and solar energy. Aquaponics systems that match the type of fish to the region — for example, tropical fish in warmer regions — do not have the added expense of heating the water in cooler weather.8
Because the systems aim to be “closed loop” — reusing waste flows to minimize inputs and outflows — there is little to no waste and no run-off generated in well-designed hydroponic systems.10
Because hydroponic and aquaponics systems can be established anywhere — from tight urban spaces to remote rural places — once they are established, they can be a source of local produce and/or fish that can help reduce food insecurity.11
Systems that are established at a scale larger than personal use can provide local sources of fish and produce to the community. The goods can be sold directly to consumers on site or at farmers’ markets, or can be delivered through CSAs.12
Low resource requirements can make the systems easy to establish as a means of local food production that can help communities recover after disasters. In addition, their designs make them less vulnerable to extreme weather conditions like heat, droughts and floods. For example, systems established indoors are not vulnerable to weather changes.
While well-designed and appropriately scaled recirculating systems can be an efficient way to produce some food, they aren’t a perfect answer for all crops. Many systems have high energy use that limits their potential, and poor design can hamper efficiency and impede systems from achieving a tighter loop between inputs and waste.
Depending on how and where they are established, hydroponic and aquaponics systems can have high energy costs. This is because they incorporate lighting, pumping, air moderation and — where fish are included — possibly water heating and cooling.13
Energy costs associated with lighting used to be a significant part of hydroponic operating budgets but with advancements in efficient LED lighting, those costs have come down. The true costs of set up and operation will be determined by scale, location and whether the system is set up outdoors where it can take advantage of sunlight, or indoors where artificial lighting and air movement will be required.
For aquaponics systems established where the climate is not suited to the type of fish being grown — for example, growing tropical fish like tilapia in colder climates — water heating might be required, which could significantly increase energy costs.14 Additional energy requirements include water circulation via pumps.
Water requirements for hydroponics and aquaponics systems are generally low compared to land farming.15 Meeting the initial water requirements is generally not an issue, unless the system is located in a water-stressed environment or there is not a ready source of water; for example, a system located in an empty city lot where there is no plumbing infrastructure in place and water must be obtained from offsite sources like fire hydrants. Once the initial water supply is in place, make-up water needs are generally minimal.
Depending on the type of fish raised in aquaponics farms, feed can present a challenge. Fish that are carnivorous are often given feed made up in part by small, wild fish taken from the sea, like menhaden.16 These fish are a primary food source for marine wildlife — dolphins, birds and larger fish — and are also critical to the diets of many coastal communities worldwide.17 Many aquaponics farmers raise fish (like tilapia) that can be fed a vegetarian diet; however, this type of feed often includes grains like soy and wheat and other commodity crops that are dependent on industrial farming practices. Many farmers find other, more sustainable sources of feed for their fish, such as duckweed or black fly larvae.18
Compared to traditional farming, hydroponic and aquaponics systems can have low start-up costs, primarily because large amounts of land are not required. But depending on the scale, system design and location, the initial and operating costs can be significant.
Initial costs include the cost of acquiring land/buildings or rent on those spaces, equipment like tanks, pumps, tubing/hoses and plant rafts, energy for lighting and heating, water (if a ready source does not exist, as might be the case in a rural location or in an abandoned urban lot), materials, plant starters, fish frying and building supplies.
Ongoing costs include labor, energy usage and fish feed for aquaponics. When all costs are considered, the bulk of the costs come from energy use and labor, and (depending on the set up), potentially, rent.19
Some enterprising companies are preassembling hydroponic kits in cargo containers and selling everything required to start a hydroponic farm just about anywhere, for a set price.20 The setup could be more challenging with the jump to aquaponics, as the addition of fish brings additional requirements for heating, fish feed and additional space.
Hydroponic farms have capitalized on inexpensive labor, land and energy in regions like Appalachia, where their relative proximity to large cities makes shipping produce relatively easy. However, as these farms become more profitable, some community members have voiced concern that the increase of automation in large facilities could quickly make some of the jobs they create obsolete.21
Both hydroponic and aquaponics farms are receiving a lot of attention in the media which is helping to build their success. There is growing interest from venture capitalists to establish large-scale systems, primarily in hydroponics. Guides that explain typical start-up costs indicate that hydroponic farms can become profitable quickly depending on the set up.22 Aquaponics systems that have strong educational components and are run as nonprofits tend to do better than commercial aquaponics ventures.23 There are fewer commercially successful aquaponics farms than there are hydroponic farms around the country.
Some studies have compared the profitability of aquaponics farms to that of small land-based farms and found they tend to be similar in size and gross sales revenue. They also found, similarly, that aquaponics farmers often must take off-farm work to earn a viable income.24 This is true for many small farmers in that much of their household income stems from off-farm activities.25
Research suggests that, like other small farms, aquaponics farms tend to be more profitable if farms diversify their revenue stream, for example, by selling non-food products and aquaponics-related services, or conducting educational trainings.27
While some hydroponic and aquaponics producers have received organic certification, there has been a debate over whether crops grown without soil can be included within the scope of organic production. Given the organic label’s focus on improving soil quality, some land-based farmers have argued soil-free methods don’t qualify. However, the National Organic Standards Board recently voted not to exclude hydroponic and aquaponics farms from organic certification.28
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