Soilless systems have become very appealing options for the modern gardener. They tout many hefty advantages, from the cost-savings of a closed loop water system to the reduced environmental impact that uses less resources than soil gardening.
With the growing popularity of soilless agriculture, however, has come the growing number of available options. Choosing between the multitude of setups on the market can be a daunting task, so read through this guide to help you begin navigating the waters of soilless agriculture.
Soilless agriculture comes in two main varieties: hydroponics and aquaponics. Hydroponic systems are generally set up with plants held in soilless growing beds where water is routinely flushed through the system after being chemically treated by the gardener to be very nutrient-rich. We’ve written a helpful review of the top hydroponic nutrients that’s definitely worth taking a look at before buying your nutrients.
Aquaponics uses a hydroponics system that is paired with an aquaculture system raising aquatic animals, usually for harvest. The plants and animals have a symbiotic relationship where the animals, most commonly being fish, but sometimes also crustaceans and mollusks, produce waste that the plants use for nutrients. The plants cleanse the water for the animals, and the system cycles water back to the animal tank from the plants and back again.
Aquaponic Pros and Cons
Pros | Cons |
| Harvest plants and fish for food | Learning curve in caring for aquatic animals |
| Don’t have to buy nutrients or fertilizer | Water chemistry can be trickier when adding fish |
| Holds equilibrium on its own | Additional cost of fish and their care |
| Don’t have to dump or cycle water | |
| Lower risk of root rot |
Hydroponic Pros and Cons
Pros | Cons |
| Simpler setup than aquaponics | Requires water dumps |
| Requires less space | Time and financial cost of fertilizers |
| Cheaper in initial setup costs | |
| Harvest plants faster than aquaponics | |
| Lower heating costs (if any) |
Which is better, hydroponics or aquaponics? Let’s take a look:
Benefits of an Aquaponic System
Harvesting both plant and animal food from the same system
Since aquaponics combines hydroponics with aquaculture, a gardener that chooses this type of system is able to harvest across the different food groups rather than just the plant foods that you would get from a hydroponics system on its own. A comprehensive aquaponics setup could provide an entire meal’s worth of food from your own labor. We’ve provided a list of the best plants to grow using aquaponics.
No need to purchase fertilizer
Because of the relationship between the animals living in the aquaponics system and the plants growing, a gardener using aquaponics won’t have to spend any extra cash on fertilizer or other plant foods. The fish eat their food—either a commercial food or some people choose to use food scraps from their own kitchens, depending on the fish living in the system—and then produce waste that is transformed naturally by bacteria that already resides in the water into fertilizing compounds. This can be flushed directly into the plants’ growing beds without adding extra fertilizers.
System holds equilibrium on its own
You can owe this one to the fish-plant relationship as well. Aquaponics systems are built to mimic a natural ecosystem and, as long as the gardener is diligent in getting the initial setup built correctly, it will be able to maintain the balance between the needs of the fish and those of the plants.
After the fish produce the waste that is converted to a natural fertilizer, the waste water flows into the growing beds where the plants suck the converted waste compounds out of the water, leaving behind pure, naturally filtered water. This can then be immediately drained back into the fish bin, where the cycle can start over with no intervention necessary. This balance makes aquaponics easier to maintain after initial setup than hydroponics alone.
No routine water disposal
Since an aquaponics system is able to maintain the chemical water balance on its own, the gardener doesn’t have to worry about dumping and cycling in new water as a regular practice, unlike gardeners choosing hydroponics. Much like common household fish tanks, hydroponic systems get chemical buildup in the water that requires the gardener to often change a portion of the water in the system or else it kills the plants living in it.
The chemical buildup in hydroponic systems are a result of the added fertilizers that the gardener must supplement in order to feed the plants. This requires the gardener to have a planned disposal method to prevent environmental damage. With an aquaponics system, a gardener can avoid all of that.
Lower risk of root rot
Root rot happens when bacteria and fungus grow in the water and eat away at the root systems of the plants growing in the system. In hydroponics, root rot is a frequent issue gardeners face.
In aquaponics systems, the setup mimics an ecosystem and prevents this from happening by keeping the fungal and bacterial colonies in check.
Disadvantages of an Aquaponic System
Learning curve in caring for aquatic animals
For gardeners who don’t have previous experience with aquatic animals, there can be a definite learning curve in getting the hang of caring for the fish in the aquaponics system. Before a gardener can get started in aquaponics, they have to be well-versed in the different choices of aquatic life and what environmental conditions they require to thrive, such as water pH, temperature, aeration, and stocking density. Getting these things wrong can cause the fish to get sick or die, which means a gardener could face major setbacks in the beginning.
Fish like tilapia, trout and catfish are some of the best fish for aquaponic systems.
Water chemistry can be trickier when adding fish
Before an aquaponics system can support itself, a gardener has to get the water chemistry just right so that the fish are able to thrive in their environment and aren’t producing too much waste for the plants to filter. Getting this balance wrong can cause fish to die, further throwing off the water chemistry, or slowing the growth of your harvest.
One of the best ways to achieve this balance is by buying a pH meter for hydroponics. Once you know where your levels are, you’re able to control it.
Additionally, fish can’t be mindlessly dumped into an untreated bin of water in the beginning. Before the fish arrive, the gardener has to have the water of the system running on its own and primed to be at the correct pH and other requirements so that the fish are able to transition to life in the bin without issue. This extra step is essential, but can be tricky if the gardener isn’t familiar with it.
Additional cost of fish and their care
There’s also the financial cost of having to purchase fish and the equipment they need to live in addition to purchasing a hydroponic system. The fish and other aquatic life a gardener may choose will also require regular feedings, which can be quite pricey in the case of raising carnivorous fish. If fish get sick, they will need medicinal treatments, and will need to be replaced if they die or when they are harvested for food. Some fish can breed in captivity, but if a gardener chooses a variety that can’t, will have to routinely invest in new fish stock. Further, some fish, like koi, can live for decades, so you have to have a long-term plan for what you are going to do with your fish stock.
Aquaponics systems are good for people who enjoy working with animals and like working through the puzzle of setting up a self-sufficient ecosystem. Someone with the financial and time budget for a larger initial investment could benefit from choosing aquaponics over hydroponics.
Benefits of a Hydroponic System
Simpler setup than aquaponics
Hydroponics completely skip the fish part of the aquaponics equation, so the initial setup is simpler to plan out and doesn’t require as much water priming before the system can begin functioning. This makes hydroponics a potentially better choice for someone new to the hobby or someone looking to include children in the planning process.
Requires less space
Many of the aquaponics fish options—and virtually all of the harvestable ones—are rather large and require a good amount of space to thrive, especially if the gardener hopes to harvest often and requires a larger stock. For people looking to explore soilless gardening with limited space, hydroponics might be a better choice since you can eliminate the fish bin completely and save space or replace that bin with growing beds of harvestable plant foods.
Cheaper in initial setup costs
Without having to invest in fish and the equipment they require, hydroponic systems won’t require as much financial resources with the initial setup.
Harvest plants faster than aquaponics
Because hydroponic systems don’t require the gardener to wait for their fish stock to begin thriving to start getting fertilizer for their plants, hydroponic setups require less time to start getting harvest from the garden. Aquaponics requires that the gardener begins planning and building well beforehand if they expect to be harvesting all throughout the growing season. Hydroponics takes that wait out of the equation.
Lower heating costs (if any)
Aquaponics systems generally have to be kept at higher temperatures than hydroponic systems, as most popular aquaponic fish prefer warmer waters. Additionally, hydroponic setups rely on cool temperatures to ward off fungal and bacterial growth that can cause root rot. This means someone choosing a hydroponic system will be able to forgo water heaters in the vast majority of cases and save costs on energy use, whereas heaters would be necessary if the gardener had opted for an aquaponics system.
Disadvantages of a Hydroponic System
Requires water dumps
Because the plants are being supplemented artificially with fertilizers, rather than being a part of an ecosystem as in aquaponics, hydroponic systems require routine water dumps to maintain the cleanliness of the water. This makes hydroponics a bit more time consuming on the maintenance front than aquaponics, and a gardener running one of these systems must have a plan of how they are doing to dispose of the tainted water.
Time and financial cost of fertilizers
Without fish and bacteria naturally producing plant food for you, a gardener choosing hydroponics will have to measure out and add any fertilizers themselves. This process can be time-consuming, especially if you’re new to this process, and requires routine investment into fertilizer supplements, which can be expensive over time. If you don’t pay close attention to what fertilizers you add and when, the plants can easily be overwhelmed with a certain compound and your harvest will suffer as a result. Fertilizing with a hydroponic system is much more hands-on and pricier than fertilizing with an aquaponics system.
Hydroponic gardens are good for people who are very detail-oriented and like being in control of their gardens. Since you’re the one doing all of the fertilizing and water cycling, you know exactly what’s going into your system and what’s coming out. Hydroponics are also preferable for people looking for a quick and cheap option to explore if soilless gardening is right for them before making the leap into larger projects, or for people who are not looking to harvest any fish from their garden.
For some insight into the commercial factors, check out this video that talks about the markets for foods coming from hydroponics versus aquaponics:
On a surface level, hydroponics versus aquaponics simply comes down to one using fish, while the other does not. However, as you now know from our guide above, it’s much more nuanced than that. We hope our handy guide helps you determine which system is best for you.
