6 Types of Hydroponic Systems & How They Work
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Hydroponic systems, in one form or another, have been used throughout history.
What is hydroponics? Hydroponics involves growing plants in nutrient-enriched water rather than soil. Growing plants in a hydroponic system makes nutrients, oxygen, and moisture readily available, resulting in faster production and larger harvests.
There are countless strategies for setting up your own hydroponic garden, but they’re all based on six main types of hydroponic systems:
- Drip System
- Ebb and Flow (also called Flood and Drain)
- Wick System
- Deep Water Culture
- Nutrient Film Technique
In this article, you’ll learn more about the background of soil-less growing and more details on how each system works along with its pros and cons.
Let’s get started!
What Are Hydroponic Growing Systems?
Hydroponic systems fall into 2 main categories:
- Active systems that use electricity to circulate or oxygenate the water
- Passive systems that don’t need any electrical power to run
Most systems are active, meaning that you utilize an air pump, a water pump, a timer or all of the above to move water and air through the system. The concern with active systems is that the plants are totally reliant on the pump(s) to get the nutrition and oxygen they need, and your plants may suffer or die if you lose power for more than a few hours at a time.
Passive systems allow you to set the system up, introduce your plants and then let the system take over. The plants absorb the nutrient solution, and you’ll just need to top it off periodically to keep the system going.
While this method certainly works and is easier to manage, passive systems usually cannot support large plants or those that produce flower or fruit harvests. Instead, they’re most ideal for foliage crops, including these:
- Leafy greens
Depending on the active system you choose, you could grow almost anything hydroponically, although root vegetables and large, sprawling plants (like pumpkins) can be a challenge.
How Do Hydroponic Systems Work?
Hydroponic systems operate on the principle of delivering water and nutrients directly to the plant’s root system. If you’d like to learn more about studies done on hydroponic growing, the U.S. National Agricultural Library has some great information.
While not every system uses all of these, the following are common features in hydroponics:
- Grow media
- Air pump
- Water pump
Let’s look at each of these in a bit more detail:
Water. All hydroponics systems use water as the primary source of nourishment for the plants.
All plants need water to survive and thrive. When growing in soil, plants expend quite a bit of energy in stretching out their root tips to seek out moisture in the soil. In hydroponics, water is readily available to plants to absorb, allowing them to redirect the energy they would have spent on searching for moisture into bountiful foliage, flower and fruit production.
Nutrients. Soil naturally contains minerals and nutrients that plants absorb through their root system. But the levels of soil nutrients can vary significantly from one location to another, even within the same garden. Hydroponic growing involves adding specially-formulated fertilizers to the water, creating a nutrient-rich solution that’s carefully balanced to meet the plant’s nutritional demands.
Here again, by making all the essential nutrients readily available to your plants, you have more energy directed at producing a harvest instead of searching for nutrition. Also, you can provide the perfect nutritional environment for your plants at all times- something that’s difficult or impossible to do with soil.
Grow Media. Since water is a liquid whereas soil is solid, your plants will need a little help to stay anchored and supported while they grow in your hydroponic system. This is where grow media comes in.
Grow media is made of inert materials whose sole purpose is to hold your plant steady in the system- they don’t add any nutrients of their own to the system.
These are some of the most common types of grow media:
- Hydroton pebbles
- Coco coir
Air Pump. In active hydroponic systems, growers use an air pump to add extra oxygen to the water. Standard water already contains dissolved oxygen molecules, but not in the quantities needed to allow a large plant to thrive and produce a harvest. An air pump paired with an air stone creates an oxygen-rich environment for the plant.
However, not all hydroponic systems use an air pump. In passive systems, the plants absorb water through their roots, and as the water level drops, the roots naturally get exposed to air. In intermittent-flow systems, the plants are not continuously submerged in water, so they can absorb oxygen from the ambient air between water exposure.
Water Pump. A water pump is used to circulate nutrient solution throughout the hydroponic system.
Here again, not all systems require the use of a water pump. Typically, ebb and flow, nutrient film technique and drip systems require a water pump, while aeroponics, deep water culture and wick systems do not.
6 Types of Hydroponic Systems
Now that you’ve got a better idea of the background information, let’s take a deeper dive into how each of the six types of hydroponic systems works.
1. Drip Hydroponics
In drip hydroponics, the plants are fed through an irrigation system rather than having direct contact with water in a reservoir.
The plants grow in an upper bed, typically in individual pots filled with grow media, and a drip line goes directly into each pot. A lower reservoir contains oxygenated nutrient solution, and a water pump sends the solution through the irrigation lines to individual pots. Excess nutrient solution drains downward back into the reservoir, where it can be reused for the next irrigation cycle.
One great thing about drip systems is that you can start your plants from seeds within the system itself. With most hydroponic setups, the plants get their water/nutrients from below, so the plants need to have an established root system before they can go into your system.
But since drip systems feed the plants from above, seeds get the moisture and nutrition they need to sprout and spend their entire life cycle in the system.
Drip systems can use a horizontal grow bed, like the illustration above, or utilize vertical space, like this tower design:
A well-planned drip system is extremely efficient, using a minimum of nutrients and water but still giving each plant plenty of nourishment. Even though it’s not too difficult to set up a small-scale drip hydroponic system for home use, it’s much more common to see drip systems used on a large-scale or commercial set-up.
Pros of Drip Hydroponic Systems
- Highly efficient for growing lots of plants with minimal inputs
- Can start plants from seed in the system
- Ideal for large-scale operations
- Can be used vertically or horizontally
Cons of Drip Hydroponic Systems
- Cost may be too high for small-scale systems
- Plants may die quickly if the power fails
You can view one way to build a drip hydroponic system and see it in action in this video from Eddy’s Greenhouse Garden:
2. Ebb and Flow (Flood and Drain)
Ebb and flow systems also go by the name of “flood and drain” systems.
When we asked Laurence Lee, hydroponic grower and CEO of The Great Brain Experiment, about his thoughts on hydroponic systems, this is what he had to say:
“My personal favorite system is the ebb and flow system. The ebb and flow system uses a container filled with water and a pump to flood the plants with water for a set amount of time. After the water has flowed over the plants, the pump automatically turns off and the water drains back into the container. This process is repeated a few times a day.”
While the pump is not running and the excess nutrient solution has drained (or ebbed) back into the reservoir, the plant roots are suspended in the air within the tank. This allows the plants to easily absorb all the oxygen they need to thrive and produce their harvest.
You can create an ebb and flow system from a standard grow bed, like we show in the illustration above. Some home hydroponic growers also design a system of connected tanks to create a recirculating system, like this setup made with 5-gallon buckets:
Ebb and flow systems are ideal for any kind of crops you’d like to grow, whether you have an indoor or outdoor setup. Leafy greens and lettuces will typically produce the fastest harvest. But larger, fruiting plants, like tomatoes or cucumbers, will also do well in this system type.
Pros of Ebb and Flow Hydroponic Systems
- Gives plants plenty of nutrients and oxygen
- Can be a single grow bed or be scaled up to a larger recirculating system
- Ideal for growing any type of plant
Cons of Ebb and Flow Hydroponic Systems
- Loss of power can damage plants
Here’s a video from Hoocho showing a simple ebb and flow set-up:
3. Wick Hydroponics
In wick hydroponics, the plants sit in grow media in a bed that sits above a reservoir of nutrient solution. A strip of absorbent material, typically cotton or felt, is suspended between each plant’s root system and the lower reservoir. This strip wicks nutrient solution upward from the reservoir and delivers it directly to the roots, where your plant can absorb it.
An air pump and air stone are optional components. But wick hydroponic systems can also be totally passive, meaning that they can function without any electrical components.
This system is ideal for producing leaf crops, like lettuces, leafy greens and herbs. If you’d like, you can set up a mini wick system that can easily fit on your countertop for a continuously fresh supply of salad and cooking ingredients.
One of the primary draws of wick hydroponics is that it’s easy to set up and maintain. The plants draw the nutrient solution as needed, so it’s also a very efficient system that only requires minimal water/nutrient inputs.
And since the air pump is an optional component, your system can still run without a hitch even if you lose power.
Pros of Wick Hydroponic Systems
- Excellent system for hydroponic beginners
- No electricity needed if not using an air pump
- Inexpensive to set up
- Perfect for leafy greens and herbs
Cons of Wick Hydroponic Systems
- May not be able to support large plants or those that produce lots of water-rich fruits
To see a moderately-sized wick system build, check out this video from Happy Hydro Farm:
4. Deep Water Culture
Deep water culture (abbreviated DWC) is one of the most common home hydroponic methods. One reason growers like it so much is that you can get your system up and running quickly with just a few simple components, and DWC gives you the flexibility to have a small setup or scale up to a larger one.
In DWC, a plant’s root system is completely submerged in nutrient-rich, oxygenated water. This gives the plant plenty of access to the elements it needs to grow, and the plant spends its entire life cycle in the DWC system.
One drawback to DWC is the fact that it consumes a lot of water. Instead of recycling the same nutrient solution many times through the system, a DWC tank needs to stay full continuously for the plant to live.
A variation on the DWC concept is recirculating deep water culture (RDWC). Instead of individual reservoirs with their own air pumps, RDWC involves connecting several reservoirs to one central air pump and the addition of a water pump.
The water pump forces oxygenated nutrient solution through the system in a circuit that feeds each individual reservoir.
RDWC is a great way to scale up the DWC system for a greater harvest with less nutrient input and lower cost for separate air pumps.
Pros of Deep Water Culture Hydroponic Systems
- Simple to set up and uses inexpensive components
- Can grow large, fruiting plants like tomatoes and cucumbers (if the reservoir is large enough)
- Can scale up for a larger system
Cons of Deep Water Culture Hydroponic Systems
- Requires a lot of water
Joe’s Hydroponics demonstrates a 12-gallon DWC set-up in this video:
Aeroponics is an active system that uses a high-pressure air pump to intermittently spray your plant’s roots with nutrient solution through mister or spray heads. The real beauty of aeroponics is that the plants stay suspended in the air, allowing the roots to have incredible oxygen uptake while still getting the nutrients they need.
Another benefit to aeroponics is that the system requires less water and fewer nutrient inputs, making it extremely efficient. And aeroponic growers usually report the highest yields and fastest harvests of any hydroponic set-up, thanks mostly to the constant oxygen exposure.
You’ve also got some additional freedom to decide how you want to set your system up. Most growers use foam or rubber plant collars to hold their plants steady in the system, but you could also opt to use net cups with grow media if you choose. And some growers prefer to use an air pump with lower pressure to produce more of a nutrient shower than a mist.
Here again, you’ve got the option to use a horizontal grow bed or decrease your footprint by going vertical. This photo shows a home system that uses vertical space:
However, set-up costs are typically higher for aeroponics set-ups, and the system is a bit more complicated since you’re dealing with a specialized air pump, and maintenance/troubleshooting can also be trickier.
Pros of Aeroponic Hydroponic Systems
- Excellent plant production
- Minimal water and nutrient inputs
- Can be adapted to your preferences
Cons of Aeroponic Hydroponic Systems
- Higher initial cost
- Maintenance and troubleshooting may be more complex
- Very susceptible to power outages
See how to set up a simple aeroponic system as demonstrated by Green Our Planet:
6. Nutrient Film Technique (NFT)
Nutrient film technique (NFT) uses a series of gently sloped grow trays to expose the plants to a continuous flow of nutrient solution. A water pump forces nutrient solution to the highest point in the system, and the sloped sections naturally drain the water downward and back to the reservoir where it can be pumped through the system again.
Even though the flow is constant, the water level stays very shallow, with just the lower sections of roots being submerged. This design results in a “film” of nutrient solution, which gives the system its name.
The rest of the plant’s roots are exposed to oxygen, so the plants get a perfect balance of both nutrient and oxygen uptake.
Thanks to this design, NFT systems can produce robust crops of leafy greens, lettuces and herbs. You could also grow fruiting plants, like tomatoes, in an NFT system, but you’d need a larger build to accommodate the plant’s larger root system.
NFT systems can use long sections of piping connected together, as the first photo below shows. If your space is more constricted, you can also build a more compact system, as shown in the second photo:
Pros of NFT Hydroponic Systems
- Balance of oxygen and constant nutrient exposure can grow large harvests
- Continual water flow avoids nutrient build-up in the system
- Requires no or very little grow media
- Highly efficient use of water/nutrients
Cons of NFT Hydroponic Systems
- Small growing area cannot support plants with large root systems
- Completely dependent on electricity to keep water flowing
This video from Hoocho does a great job of showing how to build a larger-scale NFT system:
Shopping for Hydroponic System Kits
There are a multitude of ways to build a custom hydroponic setup that meets your needs. If you’d like to get some inspiration and ideas to do just that, we’ve covered beginner-friendly options in our post on DIY hydroponic building plans.
But if you’d like to explore hydroponics without the time and effort of building a custom setup, buying a pre-made system is a perfect option. Here are some suggestions to consider:
AeroGarden Harvest Indoor Hydroponic Garden
The AeroGarden Harvest is a 6-plant hydroponic system that uses a low-flow aeroponic design and is compact enough to sit right on your kitchen countertop.
Each plant grows in a separate pod, and the AeroGarden circulates nutrient solution intermittently while still giving plants abundant oxygen exposure. The front panel has lights that let you know when to add more water or plant food to the system, and a full-spectrum LED light automatically runs to give your plants the light exposure they need.
The Harvest is the base model, and there are various other AeroGarden options to choose from.
Click and Grow Smart Garden 3
The Click and Grow Smart Garden 3 holds 3 plant pods and is another option that’s perfect for a countertop or kitchen table.
This is a wicking hydroponic system that doesn’t use any electricity to deliver water to your plants. Each plant pod comes with nutrient-rich grow media, and the overhead LED light runs on an automatic timer to give your plants plenty of UV exposure. So all you need to do is add water to the reservoir tank and keep it topped off.
If you’d like a little more growing space, there are several other indoor gardens in various size options, which you see on the Click and Grow website.
RELATED: To see how these systems stack up, check out our side-by-side comparison of AeroGarden and Click and Grow!
Hydrofarm Root Spa 8, 5-Gallon Bucket System
The Root Spa System from Hydrofarm is a deep water culture setup that includes:
- 8 5-gallon buckets
- 1 air pump
- Airline tubing
- Connectors and fittings
- Net pots
This system is a great way to get started in hydroponic growing using one of the most popular home techniques of all- deep water culture. Connect each bucket to the central air pump, add water and nutrients, then fill your net pots with grow media and plants. It doesn’t get much easier than that!
One unique aspect about this system is that you do not need an air stone- usually an essential component of DWC. But Hydrofarm uses perforated tubing that releases air from the the tubing itself, bypassing the need for a separate piece and keeping things a little simpler.
Active Aqua Grow Flow Ebb & Gro 12 Site Hydroponic System
This pre-fabricated system from Active Aqua includes:
- 12 2-gallon growing pots
- 1 55-gallon reservoir drum
- Basic nutrients
- Water tubing
- Flow regulator and timer
- Connectors and fittings
Once you’ve assembled your system, fill the pots with grow media of your choice (expanded clay pebbles are a popular option) and add water and nutrients. Settle your plants in the pots, and set your preferred schedule for the ebb and flow cycle to run.
Why Are Hydroponic Systems Better Than Growing in Soil?
There are plenty of reasons why hydroponic growing is the superior choice in many situations:
- Starting a hydroponic garden is a perfect way to enjoy fresh produce year-round, regardless of the weather in your region.
- Plant roots in a hydroponic system tend to stay more compact since they don’t have to spread outward in search of nutrients. This allows you to grow more plants in a smaller area compared to soil gardening, and some hydroponic systems have a vertical design to capitalize on space even more.
- Many hydroponic systems can be run completely indoors, so you don’t need to have access to ground or outdoor space for a traditional outdoor garden.
- Since nutrients are abundantly available to your plants, growth and production rates tend to be much faster.
- Many systems only require simple, inexpensive components to build. And various types of hydroponic system plans are readily available online, so there should be one to suit any growing conditions.
- You have complete control over the nutrient levels your plants receive, so you can ensure your plants have everything they need to thrive and produce bountifully.
- Hydroponically-grown plants usually have fewer pests and plant diseases.
- Once you get past the initial learning curve, it’s easy to develop an effective growing strategy you can replicate over and over.
Is Hydroponic Growing Worth It?
Hydroponics bypasses many of the common problems of soil gardening, including soil nutrient depletion and adverse weather.
But the biggest benefit of hydroponic growing is the ability to turn almost any space, indoor or outdoor, into a wildly productive garden. You don’t have to have a large piece of land to work with to grow your own fresh produce right at home.
When it comes to the price tag, hydroponics can be the more cost-effective growing method over time compared to soil. Set-up costs vary depending on which hydroponic system you choose to go with and the size of that system, but very simple systems can cost less than $50 and produce a nice crop of leafy greens and herbs.
For more complex systems, the initial investment is obviously higher. But with proper care, you can reuse your system reservoirs and other components multiple times. The only ongoing costs you face are system nutrients and the cost of electricity to power a timer and air/water pumps.
As opposed to buying fertilizers and potentially fresh soil every year if you garden in containers, a hydroponic system can cost less over the long term.
Frequently Asked Questions about Hydroponic Systems
Hydroponic systems have come a long way since their inception, and the development of new techniques and creative at-home builds has exploded over the last 50 years.
No matter how much or little space you have to work with, there’s a hydroponic system out there that can turn an empty area into a thriving garden. All it takes is some creativity and effort on your part!
We want to hear from you! Do you have any other questions about hydroponic systems and how they work? If you’ve built one in the past, what have you learned from it? Our collective experiences may be just what someone else is wondering about, so please share your thoughts and questions in the comments!