There has been much debate as to which gardening method is more effective between aquaponics and hydroponics. You’ll see how aquaponics dominates hydroponics in a battle between hydroponics and aquaponics.
In this article, we will look at the main differences, objectively, between these two methods of soilless growing and see if aquaponics is really the better of the two methods. A next article will be dedicated to bioponics, which is still less criticizable than hydroponics 🙂
To begin with, it is important to define hydroponics as well as aquaponics.
What is hydroponics?
Hydroponics is a long proven and widely used method of growing tomatoes and lettuce, most often in greenhouses. Plants are grown directly in a water-based nutrient solution containing all the essential nutrients, minerals and trace elements required by the plants for growth and fruiting. Plants are grown in inert supports or substrates such as pebbles, clay balls or NFT pipes which are sometimes used to support plants when growing in vertical towers.
The absence of soil completely eliminates organisms and weeds. As a result, tillage, as well as the use of herbicides, is greatly reduced but allowed because there are no fish, worms or bacteria to kill (unlike aquaponics where one must ensure that the life of the ecosystem is maintained).
The controlled environment protects the crop from most atmospheric parasites. Occasional infestations and fungal infections can be effectively dealt with through the targeted use of pesticides and fungicides.
Hydroponics generally uses only 20% of the water that traditional soil-based growing requires. The main problem with hydroponics is that nutrient-depleted water must be replaced periodically. This is the main recurring cost of hydroponics. The electrical conductivity or electro-conductivity (also known as EC) of the solution is monitored daily to keep nutrient levels up. The nutrient solution must be changed when a chemical imbalance is detected. Energy requirements include aerating and pumping the solution every 4-6 hours although some systems run continuously to irrigate the roots without interruption throughout the life of the plants being grown. Hydroponics can be done indoors under artificial lighting, which makes food production possible all year round but has the disadvantage of increasing the energy bill.
Hydroponics uses only water and chemical nutrients to grow the plants. There is no need to have soil to practice this culture. Hydroponics is more developed in the world than aquaponics. We often see hydroponics in farms and industrial greenhouses in Spain and North America. Hydroponics is also the most popular growing technique among cannabis growers.
Summary of the advantages of hydroponics for vegetable gardening:
No soil is needed
Hydroponics is stable and produces high yields
There is no damage to the hydroponic system caused by pesticides
Lower water requirements than conventional soil-based growing
Allows growing in small spaces and urban areas
Summary of the disadvantages of hydroponics:
Discharge of water polluted with salts and chemical crystals from the remains of nutrient solutions
Requires the purchase of fertilizers
There is no life in a hydroponic system
Hydroponics is rarely organic
The food produced is of poor quality, tastes like water and is poor in nutrients because hydroponists only focus on N, K and P nutrients
What is aquaponics?
Aquaponics is a complex culture method that has evolved as an effective solution for recycling waste generated in aquaculture. Based on the wetland ecosystem in which plants and animals support each other, the nitrogenous waste produced in fish or crayfish aquaculture is used as fertilizer for hydroponically grown plants. Aquaponics is based on the nitrogen cycle found in nature. An aquaponics system is naturally full of nitrogen and bacteria and worms help break down the fish waste into nitrates and nitrites that can be taken up by the plants. The water in an aquaponics system is clean, is not recycled, and runs in a closed loop.
The only input required in an aquaponics system is fish food, plus the electricity needed to run the pumps that circulate the water between the grow tanks and the fish tanks. The only water loss in aquaponics is mainly from transpiration of the plants and evaporation into the atmosphere. The rate of water evaporation is so low that it is claimed that aquaponics saves between 90 and 95% of the water that would have been needed for conventional soil cultivation.
Summary of the advantages of aquaponics for vegetable gardening:
- No soil is needed
- The aquaponic ecosystem is stable and balanced
- Aquaponics is organic by default: you can’t treat or you will kill the fish and the life in the system
- There is no water discharge because the water is in a totally closed circuit
- The only input required is fish food
- 90 to 95% water savings compared to conventional culture and 10 to 15% compared to hydroponics
- Allows to produce plants but also organic and ultra-fresh fish
- The food tastes fabulous and is rich in nutrients
- Aquaponics is less expensive than hydroponics because there are few inputs required
- You can produce food for your fish for free (vermicompost, slugs, larvae, etc…)
- Allows cultivation in small spaces and in urban areas
- Contrary to hydroponics, in aquaponics the vegetables have a real natural taste
Summary of the disadvantages of aquaponics:
- In aquaponics you have to find the right compromise between the pH for the plants and the assimilation of nutrients and the pH for the fish which limits to a pH of 6.8 to 7.
- Aquaponics requires a little knowledge in aquarium keeping
- Risk of losses in case of mechanical failure. No mechanical system is infallible. Electrical failure, mechanical faults, blockages in plumbing and malfunctioning monitoring devices can disrupt system operation. In hydroponics, most problems can be resolved immediately without causing lasting damage because they are commonly 5-6 hour flood and drain cycles. In aquaponics, the cycles are very short, several times every 30-45 minutes, so the cost of even a temporary failure can be particularly high, often resulting in the loss of fish. The solid waste produced by the fish also makes the aquaponics system relatively more prone to blockages in the event of poor water filtration.
We have covered the basics, now let’s get into the details.
The differences between hydroponics and aquaponics
Hydroponics and aquaponics share many similarities as aquaponics is 50% hydroponics. Both of these above-ground growing methods use nutrient-rich water that is highly oxygenated to bathe the plant roots continuously or alternately, and both of these growing systems have the best growth rates compared to growing in soil.
Although aquaponics borrows many techniques from hydroponics such as NFT (Nutrient Film Technique) and DWC (Deep Water Floatation Technique), there are many significant differences and this is where the advantage of aquaponics over hydroponics is clearly seen.
The cost of chemical nutrients
In a hydroponic system, the chemical nutrients used to feed the plants are expensive and the costs are continually rising due to their near scarcity. In an aquaponics system, fish food is used instead of these chemical nutrients, which is not only cheaper, but will provide all the nutrients needed for your plants and fish to thrive. Also, in aquaponics, you can make free food for your fish by raising worms, larvae, slugs, caterpillars or other insects that the animals are fond of. You can also prepare food for them with everyday foods such as pasta, salads, vegetables and other algae.
This is perhaps the biggest drawback of aquaponics compared to hydroponics. In hydroponics, you simply add commercially formulated nutrients to the water in your system and it works. In aquaponics it takes about 20 to 30 days to cycle your aquaponics system by developing a colony of nitrifying bacteria through a process called “nitrogen cycling”. Ammonia from fish waste will not be converted to nitrates until the system is cycled.
The relationship with bacteria
In hydroponics systems tend to be almost sterile. In general, in large hydroponic facilities you have to wear coveralls and a hair net before entering. Nothing like that in aquaponics. Bacteria are revered by aquaponic gardeners because, as described above, they are the lifeblood of their systems. Aquaponics does not fight nature, it is inspired by it.
Hydroponic growers use flood and drain techniques generally only to fertilize their plants once every four to six hours. Academic studies and extensive collective experience have shown that this is the optimal amount of time to provide the water and fertilizer the plants need. In aquaponics, there are floods for 15 minutes every 45 minutes, and sometimes the reverse. The culture bed has now taken on the additional role of a biofilter for the fish waste. You need this tidal alternation if you want your biofilter to be effective. If you follow the hydroponics model in aquaponics, toxic substances would be stored in the fish tank and that would be bad for them.
The depth of the growing bed
Professional hydroponic growers tend to use standard deep flooding tables and put pots or cubes with plants in them. These are called flooding trays. Again, because the substrate in an aquaponics system has a dual role as both a substrate for the plants and a bio-filter for the fish waste, both must be considered and optimized. Most aquaponicists use growing tanks filled with substrate about 30 centimeters deep. Over the years, you will find that this depth allows another kind of heterotrophic bacteria and red worms to grow. They too enrich the aquaponics system with new substances and are needed to break down and decompose the solid waste of the fish and the aquaponics system.
Balance of the nutrient solution
Hydroponic gardeners only preach by their nutrients, pH and fertilizers or “supplements”. Not so with aquaponic gardeners. The goal of an aquaponic gardener is to achieve a state of perennial equilibrium within their ecosystem. Everything that goes into the system must work for this end goal and not harm any other element of the system. Anything added to the system to stimulate plant growth could harm the fish and bacteria colonies as well as the composting worms. There are a few exceptions to this rule such as the use of organic fertilizing algae, small amounts of chelated iron, and some minerals to adjust the pH (example: calcium, magnesium and phosphorus supplements for home-made aquaponics). But beyond these supplements, aquaponics growers think long and hard before adding anything to their systems except, of course, fish food.
Draining the water from the system
Water containing hydroponic nutrients must be discarded and replaced regularly to correct nutrient imbalances that occur over time and to remove chemical salts and crystals that build up in the system. Aquaponic gardeners simply top off the water that has evaporated on a regular basis. The notion of nutrient imbalance is also foreign to the aquaponic gardener because he or she is almost an organic soil gardener, and just as with healthy soil, an aquaponic system continues to be enriched over time.
In hydroponics, growers are constantly concerned about disease. They often sterilize anything that comes in contact with the plants, their roots or the nutrient solution. The disease they fear most is a fungus called Pythium, or “root rot”, which is widely considered THE scourge of hydroponics. Fortunately, Pythium is almost non-existent in aquaponics. The difference is due to the fact that in aquaponics, there is a true ecosystem that is created and the bacteria and other living organisms in the system help regulate any irregularities. In addition to all of this, the very high oxygen levels in aquaponics systems as well as the activity of the composting worms to clean up dead plant material probably also helps to mitigate disease outbreaks in aquaponics. Disease is also sometimes caused by nutrient deficiencies.
One way to reduce and prevent outbreaks of Pythium in hydroponics is to make sure that the nutrient solution is never more than 20°C. Warm water is an ideal soil for fungi. It is therefore important to keep the water temperature below these levels. In aquaponics, the fuel for the plants, i.e. the fish, only have their appetite activated at certain temperatures and the hotter it is, the hungrier they are. The bacteria that keep the system alive are also more active when the water is warm or hot. Fortunately pythium is rare in aquaponics, otherwise it would not be possible to cultivate.
The optimal pH in a hydroponic system is 5.5 to 6.0. In aquaponics, you have to find the right pH compromise between plants, fish and bacteria. The optimal pH in aquaponics is 6.8 to 7.0, which is again what an organic soil gardener would have aimed for. So the pH of aquaponics is closer to that of nature.
Along with pH and water temperature, EC is the other measurement that is closely monitored in hydroponics. EC, or electrical conductivity, is a measure of the salts present in the nutrient solution. It tells you how concentrated or not the solution is with nutrients. This measurement works because hydroponic nutrients are usually delivered as mineral salts. Therefore, CE cannot be measured in an aquaponics system because the plants are fed by the organic waste of the fish, which contains very few salts. CE is therefore not a useful measure of nutrient concentration in an aquaponics system.
Aquaponics requires trust in Mother Nature, rather than a managed system that requires intense control. In general, in aquaponics, once the system is cycled (ammonia and nitrite levels have dropped to zero) and is balanced, the only measurements that need to be made are temperature, pH, and nitrates. If the nitrates are low (near zero), more fish should be added to the system and if the nitrates are high (over 50 ppm) more plants should be added or the grow tank should be expanded. It’s as simple as that.
Since aquaponics is an organic ecosystem that uses fish and other living things, special attention must be taken to control insects and pests. Even commonly used organic sprays such as insecticidal soap or neem oil could be harmful if sprayed in excess on the plants in your aquaponics system. The upside, however, is that you can engage your fish in your insect control efforts. For example, if I see an insect problem on a small plant, I will remove them from the grow bed and let them soak in the fish tank for a little while… The insects will eventually let go and then become food for the fish.
Hydroponics is a system for growing plants in highly optimized conditions. Aquaponics creates a complete ecosystem in which various living species interact to create a symbiotic whole. We use worms, algae and beneficial insects as “team members”. Each has specific functions to perform rather than trying to isolate plants and nutrients into separate, simple, definable and quantifiable components. Aquaponics is first and foremost an ecosystem where plants, fish, bacteria and worms all live together in a beautifully balanced symbiotic relationship.
It has been shown in several studies and research that once the aquaponic biofilter is fully established (after a period of 6 months), an aquaponic gardener will generally have faster and more efficient results in terms of plant growth than hydroponics. There are so many different cases that we can’t really say for sure yet, but more studies are being done in the above ground world.
Ease of maintenance
An aquaponics system is much easier to maintain because there is no need to check the electrical conductivity once a day as is required in a hydroponics system. The natural ecosystem of aquaponics means that the elements tend to balance each other, and you only need to check pH and ammonia levels once a week, and nitrate levels once a month.
Hydroponics is made of a sterile artificial environment while aquaponics is a replica of a natural ecosystem, making the growing and farming process completely organic. Hydroponic systems use expensive nutrients consisting of a mixture of chemicals and salts to feed the plants, while in an aquaponic system, plant food is made from the conversion of solid fish waste by bacteria and composting worms. This natural process results in better plant growth and lower disease rates. There are indeed natural and organic fertilizers for hydroponics, but that’s another debate that opens up… is organic really organic? 🙂
The modern concept of hydroponics has been around longer than aquaponics, but the practice of aquaponics goes back to ancient times. More and more people are beginning to realize the benefits and advantages of it and we see many commercial aquaponics projects and aquaponic farms being created.
Aquaponics has been on the back burner, but it is quickly catching up. Hydroponics and aquaponics are two landless farming systems that give significantly higher yields with minimal inputs. These techniques avoid wasting water in the soil. These intensive methods make local food production sustainable and profitable, despite the scarcity of water and fertile land.
Whether you choose aquaponics or hydroponics, the main thing is the goal: self-producing food. Since the goal is laudable, you won’t be blamed for doing hydroponics despite all the advice given on this page 🙂
I have 30 years of experience and i started this website to see if i could try and share my knowledge to help you.
With a degree a Horticulture BSc (Hons)
I have worked as a horticulture specialist lead gardener, garden landscaper, and of course i am a hobby gardener at home in my own garden.
Please if you have any questions leave them on the article and i will get back to you personally.