Do you dream of growing your own vegetables while raising fish, but don't know where to start ?
Aquaponics is a sustainable, accessible, and exciting solution for producing food independently at home.
In this article, discover the essential basics to get your aquaponics adventure off to a good start, step by step.
In an aquaponic ecosystem, fish waste (rich in ammonia) is converted by bacteria into nutrients (nitrates) for the plants, which filter and purify the water before it returns to the fish. This symbiotic system has many advantages: according to the FAO, it can use up to 90% less water than traditional cultivation, and the fish feed supplies most of the fertilisation, although iron, potassium and calcium often need to be topped up, and it allows rapid plant growth.
Aquaponics is also within everyone's reach with a little patience and monitoring. Ready to take the plunge? Follow this step-by-step guide to start your own aquaponic system at home, even with no experience in gardening or fishkeeping.
Aquaponics describes an ecosystem where fish and plants grow together in symbiosis. In practice, you raise fish in a pond and grow plants in a grow medium or on the water, without soil. The fish waste, rich in ammonia, is broken down by nitrifying bacteria into nitrites and then nitrates, nutrients the plants can take up. The plants absorb these nitrates for growth and thereby clean the water, which is continuously recycled back to the fish tank.
This closed-loop system is very economical with water, with savings of up to 90% compared with conventional growing in open soil, because the water is constantly recycled. Aquaponics thus makes it possible to produce vegetables (and possibly fish) in a sustainable, local and enjoyable way.
Before you start, decide which type of aquaponic system suits you. There are three common methods: the grow bed (with grow medium), the deep water culture (DWC) raft and the nutrient film technique (NFT).
1) The grow bed is a tank filled with grow medium (gravel, clay pebbles, etc.) into which water from the pond is pumped and then drains back down, feeding the plants. This system is very versatile and lets you grow a wide variety of plants, with a stable environment for the roots. It is also very tolerant of the unexpected: for example, if the pump fails, the damp grow medium provides a reserve for the plants, which can last a while without water circulation.
2) The raft (floating system) uses a tank in which foam boards (rafts) float, with holes holding the plant pots. The roots sit permanently in the pond water. This system is ideal for fast-growing leafy vegetables (lettuces, basil, etc.).
3) NFT (Nutrient Film Technique) circulates a thin film of nutrient-rich water through long pipes or gutters in which the plants are placed. It allows vertical growing over several levels of pipes and suits small plants well (strawberries, herbs).
Which method should you choose to start with? For a hobbyist, the grow bed is often recommended, as it naturally provides biofiltration thanks to the grow medium populated with bacteria. In other words, the media bed is simpler and more robust for getting started). It is also important to make your choice according to the space available for your set-up.
A pond for the fish: this can be an aquarium, a food-grade plastic tank, a barrel or any other watertight container. Preferably start with a medium volume (200 L or more) so that the ecosystem is stable.
A grow bed for the plants: this is where your vegetables will grow. Its size should be proportionate to the fish pond. This bed will be filled with grow medium (for a media-bed system) or will support rafts or NFT pipes, depending on the method chosen.
A grow medium (if using a media bed): essential for holding the plants in place and housing the bacteria. The most commonly used are expanded clay pebbles, non-calcareous rounded gravel or pozzolana.
A water pump: it circulates the water from the pond to the grow bed, either continuously or intermittently. Choose a pump suited to the volume of water to be moved (it should typically be able to pump the whole volume of the pond in an hour).
Pipes and fittings: to connect the pump to the grow bed and allow the water to return to the pond by gravity. 13 mm (1/2") PVC pipe is often suitable. Also provide a drainage system for the grow bed (an overflow or siphon) to prevent flooding and to ensure the flood and drain cycle if needed.
An aeration system (depending on the case): Often, the water movement created by the pump is enough to oxygenate the pond properly. But if the fish density is high or the water volume is large, an air pump with a diffuser (air stone) can be useful to enrich the water with oxygen.
Aquaponics can be set up indoors or outdoors alike, provided you respect a few criteria. Light is the first factor to consider. Placing the system somewhere with good natural light is ideal, as plants need plenty of sun every day. Keep your installation clear of cast shadows (away from north-facing walls, and from trees or hedges that would shade it).
In a flat with no outdoor space, you can set the system up near a sunny window. And if the light is insufficient, you can invest in artificial grow lights (horticultural LEDs) to top up the natural light.
The other important criterion is the ambient temperature. In a temperate climate, an outdoor system works well from spring to autumn, but winter poses a challenge. If you set up your aquaponics outdoors, make sure you can move the system under cover in winter (garage, conservatory) or else protect the fish and plants from frost.
Ideally, if you have the option, build or use a greenhouse. A greenhouse dedicated to aquaponics keeps up a favourable microclimate all year round, and your fish and plants will be sheltered from bad weather and cold while still receiving sunlight.
Place the pond in a stable, level spot that is easy to reach for maintenance. Finally, provide a safe electrical socket nearby to power the pump (and lighting if needed).
Once the equipment is in place and the location chosen, you need to start the system's biological cycle before adding all your fish and plants. This means giving the nitrifying bacteria time to colonise the filter and convert the nitrogenous waste. First, fill your pond with dechlorinated water (mains water treated with chlorine loses it after two to three days standing with aeration, but water treated with chloramines requires a conditioner, as they do not evaporate). Switch on the pump to circulate the water.
At the start, introduce very little life: ideally, carry out a fishless cycling (without fish) or with one or two hardy feeder fish. Monitor the evolution of the water quality every week using test kits: after 1 to 2 weeks, the level of ammonia toxins will rise and then fall in favour of nitrite, and then nitrate will begin to appear.
This process generally takes 4 to 6 weeks for a sufficient bacterial balance to establish itself. Be patient!
Wait until the tests show 0 mg/L of ammonia and nitrite, a sign that the biological filter is doing its job, and a few tens of mg/L of nitrate (a non-toxic nutrient, consumed by the plants). You can then gradually introduce your fish into the pond (preferably during a mild spell in spring or autumn, outside any heatwave or frost).
Introduce a few fish at a time, spacing them over several days, so as not to overload the system all at once. Likewise, plant up your grow bed gradually with easy young plants (lettuces, basil, mint, etc.) so that they start absorbing the nitrates.
During these first few weeks, check your setup every day: make sure the pump runs continuously and the water stays clear, and measure the pH and toxins every two to three days. The pH to aim for is between 6.4 and 7.5 to suit both fish and plants, with a KH (carbonate hardness) of 6 to 12 °dH to keep it stable. Once the nitrogen cycle is established, your aquaponic system is officially "cycled"!
Clean water that is well oxygenated, at the right temperature and balanced in nutrients keeps fish and plants healthy. Test the water regularly (pH, ammonia, nitrites, nitrates) and be ready to step in if something goes wrong (for example, a nitrite spike to be corrected with a partial water change).
Feed your fish in moderation: overfeeding is a common mistake. It can be tempting to spoil them, but excess uneaten food breaks down and sends ammonia levels soaring, which unbalances the whole system and can poison it. A golden rule is to give only what the fish can eat in 2 to 3 minutes, splitting the meals if necessary. In aquaponics, stocking density is calculated by weight: the FAO guide recommends a maximum of 20 kg of fish per 1,000 litres, and halving that figure, that is 1 kg per 100 litres, in ponds of less than 500 litres.
Common mistakes to avoid: Skipping cycling or adding sensitive fish too quickly is a sure way to run into problems (disease, mortality).
Going too fast or too big: do not start with a huge, complex system. A small unit of 200 to 500 L is ideal for beginners: large enough in volume to be stable, yet still simple to manage.
Neglecting routine maintenance: even though aquaponics requires little daily upkeep, a quick daily inspection round is important. Check that the pump is running, that the water level is correct (top up regularly to compensate for evaporation), and that the fish are eating well and show no signs of stress. Remove dead leaves from the plants and make sure no pipe is blocked by debris.
Starting an aquaponic system at home is an exciting and accessible adventure. Admittedly, it takes a little preparation and patience at the start, but the effort is worth it. By following this step-by-step guide, from choosing the system to cycling it, via setting up the equipment and the right habits to adopt, you have all the keys to succeed in your first steps in aquaponics. Do not hesitate to start small, to observe your ecosystem carefully and to intervene gently if needed. You will see that, over time, your small aquaponic setup will become more balanced and more productive.
Aquaponics brings not only fresh, healthy vegetables, but also an enriching everyday experience, educational for children and rewarding for anyone looking for greater food self-sufficiency. So get started without fear: even as a beginner, you can succeed in setting up your own aquaponic system at home.
Sources
Oklahoma State University Extension, Nitrification and Maintenance in Media Bed Aquaponics, Start-up time for the biological filter and the pH range tolerated in the growing bed.
New Mexico State University, Aquaponics, Circular 680, Target values for dissolved oxygen, total ammonia and nitrite.
UF/IFAS, A Practical Guide for Aquaponics as an Alternative Enterprise, HS1252, Approximate figures for fish stocking density, feeding rate, and water renewal.
Goddek et al., Challenges of Sustainable and Commercial Aquaponics, Sustainability, 2015, Distribution of feed-to-grow-bed ratios and the system's compromise pH.
SMIDAP, programme OPRA 2, rapport final, French practical experience on managing aquaponic systems and their water consumption.
Yes, indoors or in a heated greenhouse. Outdoors, in a temperate climate, it is better to wait until spring, because cycling is very slow in cold water.
There is no universal ratio, and that is precisely what the review studies on aquaponics emphasise. The balance depends on the species farmed, the composition of the feed, the plants grown and the water chemistry. The values published for leafy vegetables range from around fifteen to a hundred grams of feed given per day per square metre of growing area, which is a considerable spread. The FAO guide recommends 40 to 50 g for leafy vegetables and 50 to 80 g for fruiting vegetables: a 2 m² lettuce bed therefore needs only 80 to 100 g of feed per day.
For your first year, work from the feed rather than from the number of fish. Deliberately start at the low end of this range, then observe. If nitrates build up and the plants darken, you can increase the ration. If ammonia or nitrites start to climb, you are already too high.
As for fish density, aquaponic production guides give orders of magnitude of around 16 kg of fish per cubic metre in a well-aerated system. Start at half this figure, while the biofilter reaches its full capacity.
A cycling process that drags on beyond a month almost always comes from a parameter holding back the nitrifying bacteria, rarely from a simple lack of time. Go through the following, in this order:
Correct only one thing at a time and leave three to four days between measurements, otherwise you will never know what really made the difference.
It is never essential. Nitrifying bacteria arrive on their own, via the air, the water and the plants, and a well-oxygenated grow bed will always end up being colonised. A commercial seeding product, or better still a handful of grow medium taken from an already mature system, mainly saves a few days on the usual four to six weeks. However, no bottle can make up for a pH outside the right range, cold water or water that is still chlorinated.
In a coupled system, top-up water is used mainly to make up for evaporation and plant transpiration, not to renew the water. Guides to recirculating aquaculture work on a daily renewal of around 5 to 10% of the volume, but a well-planted domestic system uses considerably less. Mark the high water level of your pond and top up as soon as it drops by a few centimetres, using settled water at a similar temperature. A large top-up of cold water all at once does more harm than a slightly low level.
It is one of the riskiest trade-offs of the start-up phase. At night, the plants no longer produce oxygen while the respiration of the fish, roots and bacteria carries on. This is when dissolved oxygen is at its lowest, whereas it should stay above 5 mg/L.
If the noise bothers you, place the pump on an anti-vibration foam pad or switch to a submersible model, but keep the aeration running permanently. An interruption in circulation is tolerable for a few hours in a bed of damp grow medium, which holds a reserve of water around the roots. It is far less so with rafts or NFT, where the roots suffocate or dry out very quickly.
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Aquaponics kits
Aquaponics kits ready to install in the garden, on a patio or in a greenhouse, with fish tank, grow beds and pump.
Plants
Seeds, grow media, fertilisers and aquatic plants for successful growing in aquaponics, hydroponics and the vegetable garden.
Equipment Universe
The equipment that keeps a system running: soilless growing, water circulation and aeration, filtration, temperature, plumbing and lighting.
Aquaponics greenhouses
Greenhouses designed for aquaponics, supplied with their fish tank and grow towers.
Fish
Feed, monitor the water and care for your pond, aquarium or aquaponic fish.
Learning
Books and practical courses on aquaponics, hydroponics and food self-sufficiency.
