Deep Water Culture: Is This the Best Hydroponic Farming Method?

Deep Water Culture: Is This the Best Hydroponic Farming Method?
Contributor
Contributor
External Guest Writer
April 6, 2021

As traditional agricultural practices continue to provide low yield returns in a continually destabilizing ecosystem, it comes down to exploring new avenues of farming to meet the demands of the modern world.

Hydroponic farming is one such alternative to help alleviate the stress on traditional farming methods. The hydroponics market is estimated to grow at 11.3% to reach a market share of USD 17.9 billion by 2026. This is because of the tremendous potential within hydroponic farming and its many subsections such as deep water culture.

In this article, we will conduct an in-depth analysis of deep water culture. We will examine how this form of hydroponic farming works, its many benefits and subtle drawbacks, the methods available to conduct deep water farming, and the manner in which to set up a deep water farm.

What is Deep Water Culture (DWC)?

Deep water cultivation or direct water culture is a type of hydroponic farming method in which the roots of the plants are continually suspended in nutrient-rich, high-oxidized water. Unlike other variations of hydroponic farming such as the ebb and flow method, drip system, and aeroponics where the plants are only partially exposed to water, in this method the emphasis remains on total submersion.

In fact, the name “deep” water culture comes from the fact that the roots of the plants are completely submerged in water at all points. 

For this method, it is crucial to have a large reservoir when building the setup as large quantities of water are required to submerge the plants. The higher the levels of water in the deep water hydroponics system, the greater the levels of stability in the farm. This also means reduced levels of monitoring and maintenance in the long run.

Thus we see that the major departure when it comes to deep water culture has to do with sinking the roots of plants in water continually and round the clock.

How Does It Work?

A common concern for a lot of new growers when it comes to deep water cultivation system has to do with the excessive use of water to nourish plants. Plants do tend to become weak when over-watering occurs in normal conditions. In hydroponic farming, however, this is not the case.

Apart from being suspended in water, the key factors here have to do with the continual supply of nutrition for the plant. Alongside the nutrient-rich water, the plants also have access to the ideal lighting and temperatures in order to aid their growth. All these factors culminate in ensuring that the plants are well taken care of in this method.

One of the keys behind the success of hydroponic DWC is related to the constant supply of oxygen to the plants. This issue is resolved with the help of an air pump or falling pump that causes bubbles to rise up in the water. 

In the DWC method of farming, the plants receive a constant supply of oxygen along with the right levels of nutrition round the clock in order to promote their growth. Thanks to this, not only do plants grow well, but they also grow faster than average and have been known to be healthier than the versions grown on regular soil.

The success of deep water cultivation comes down to balancing the oxygen supply to the plants on a continuous basis. As the roots are submerged underwater for 24 hours in a day, it’s important to also have the air pump running across the day to help balance the oxygen levels in the water. If these equipment aren’t made available on the DWC farm, it will surely lead to the death of the plants over time.

The Deep Water Culture System

A large reservoir of water is first required to set up a deep water culture (DWC) farm. In the reservoir, an airstone that’s connected to an air pump is placed in the water. This helps to balance the oxygen supply in the water. Additionally, nutrients are also added to the water at this stage to enrich the growing medium.

All the plants that are meant to be grown in the deep water culture (DWC) farm are placed in net pots and are made to float in the water tank. The roots of the plants are completely submerged in the nutrient and oxygen-rich water at this point.

The pots used for this farm tend to be made from reusable plastic mesh, thereby allowing the roots of the plants to grow freely within the system. A normal pot with the hole in the bottom allows space for the roots to only grow in one direction. With a mesh pot, however, the roots have the freedom to grow in the direction that comes naturally to the plant. This plays a major role in helping the plant develop a vigorous root system over time.

As soon as the roots of the plants become lengthy enough to hit the nutrient-rich water, you can expect heightened growth to occur within the plant going forward. While traditionally a plant would have to wait for the roots to hit the right patch of water in the soil to achieve growth, here the roots are flooded with water, nutrition, and oxygen from an early phase. This helps to improve the overall health and development of the plant and has a positive effect on its overall life cycle.

The plants don’t face any threat of suffocating while leaving their roots underwater at all times because of the continuous supply of oxygen in the water. There should be a lot of bubbles flowing within the reservoir at all times to ensure that oxygen is being well-circulated across the system. It’s crucial that the bubbles rise up in the tank and make contact with the roots of the plants in order to oxygenate them.

Deep Water Culture Methods

There are a few variations of the deep water culture method that one needs to be aware of before setting up a farm. The first set of variations have to do with the manner in which the oxygen is supplied in the reservoir.

Aeration Methods in Deep Water Hydroponics

Air Bubbles Method

The easiest method of ensuring that there is ample supply of oxygen within a DWC farm is with the help of an air pump and airstone. They are used to create air bubbles in the reservoir and target the roots of the plants. 

An airline is used to connect the air pump with the airstone in the tank, and this helps control the volume of air being supplied into the system. The airstone is usually made out of a rock-like substance and it has a lot of miniature pores to help create the bubbles in the water. A soaker hose is also sometimes used in this system if there is a requirement for smaller bubbles.

There is a direct relation between the size of the bubbles and the level of aeration created in the water. The rule of thumb here states that the smaller the bubbles, the better the aeration. This is because smaller bubbles tend to have a greater contact surface with the water.

Falling Water Method

The falling water method is certainly the lesser popular one out of the two aeration methods available in this system. Here, the aeration is created by falling water agitating the surface of the water and making splashes in the solution.

Control over the level of oxygen in this method comes from the volumes of water being used. The larger the volume of water that's falling onto the reservoir, the greater the amount of oxygen produced because of the downward force of the water.

It is more common to see the falling water method used in commercial deep water culture systems in comparison to at-home systems.

Versions of Deep Water Culture

Apart from the manner in which oxygen can be supplied to the deep water culture (DWC) system, there are other variations of this method that are worth exploring as well.

Recirculating Deep Water Culture (RDWC)

One of the biggest downsides of the traditional deep water culture system is its inability to scale to large systems when required. In order to combat this issue, there’s a new variation available known as recirculating deep water culture.

This version is similar in a sense to the flood and drain method of hydroponic farming. Instead of draining the nutrient-rich water, however, the water never leaves the system at any point in this method.

Here, numerous buckets or containers are utilized in order to increase the supply of water circulating in the system. They are all connected to one another in order to create a giant central reservoir for the farm.

Apart from the ability to scale big, this method is also known to be fairly low in maintenance in the long run. All the nutrition, water levels, and oxygen levels need to be calibrated accurately only in the central reservoir, and this trickles down to the entirety of the farm. All the water and nutrition that is meant to feed the various plants in the system will uniformly be circulated from one container to another. 

In this method, ideally one to three plants are grown in each bucket or container. Attempting to grow more plants than that can have a detrimental effect on the roots of the plants as it can cause clogging over time.

Bubbleponics

Bubbleponics is the closest version to the traditional system of setting up a deep water culture farm. Here, the oxygen is supplied to the water with the help of an airstone and air pump as well. The only major departure comes from the use of a water pump inside the water tank in order to effectively move all the bits of nutrition to the top of the container.

Once the nutrition moves to the top of the tank and hits the roots of the plants, it falls back down and again, and this cycle continues infinitely. 

This method of DWC is especially popularly used when the plants are in the nascent stage of their development. When the roots are their shortest, they have trouble accessing all the nutrients in the water. Thanks to bubbleponics, the nutrients are continually circulated in the water and ensure that they access the roots during their vital developmental phase. 

Using bubbleponics can be great for plants as they help to speed up the growth of the seedling and increase the pace of the germination process as well.

The Kratky Method

The Kratky Method is the only form of deep water culture farming that doesn’t rely on the use of a pump. In fact, this is a very passive system that does not use any form of electricity whatsoever.

In order to supply the plants with nutrition and oxygen in this method, there is a small air gap that’s left between the surface of the nutrient solution and the roots of the plants. This allows a section of the roots to be submerged underwater, while another section is left open to the air.

How to Set Up a Deep Water Culture System

There are many ways in which you can set up a deep water culture system to match your needs as a farmer. The easiest method of securing the required equipment to start a farm would be to pick up a fully system kit. These are available online and for a wide range of budget options.

In you plan on starting your farm from scratch, you’ll need the following pieces of equipment:

  • Airline
  • Air pump
  • A tank for water
  • Pots to hold plants
  • Airstone
  • Growing media such as expanding clay or rockwool
  • pH kits
  • pH meter


All of these tools are easily available at most quality hydroponic or gardening stores. When picking out a water tank, make sure to get a model that isn't coated with a light color. You want to try and limit the amount of light passing through the tank, so ideally you should seek out tanks that have a darker tint to them.

After selecting the tank, it needs to be filled with the growing solution selected for the farm. The solution needs to cover the tank entirely and reach up till the base of the mesh pots. 

After this, it is crucial to keep a check on the pH levels in the water. The ideal range is between 5.5 to 6.5, and anything beyond these parameters can be damaging to the plants.

Next, the oxygen supply needs to be regulated. This can be done by connecting the pump to the airline, and then connecting the airline to the airstone. Once these connections have been made, the airstone can be placed at the bottom of the reservoir. 

You can now begin to place the plants in the pots and allow the roots to hit the water. Turning the pump on at this stage will kickstart the whole system.

The Benefits of Deep Water Culture

Here are some of the major benefits of DWC farming:

  • Research has shown that plants grown in deep water culture display accelerated growth. This is because there is a continuous supply of nutrition and oxygen to the plants in this method of farming. A lettuce head, for example, can grow in only 30 days in deep water culture as against 60 days when grown in soil.
  • The continuous aeration of the roots of the plants ensures that the plants have a greater ability to absorb nutrition from the medium. This has a positive effect on the cell growth rate of the plants as well.
  • As the plants remain underwater for the entirety of their growth cycle, there is no additional need for fertilizers. This has a positive effect on the health of the plants as well as preserving the soil of the ecosystems on our planet.
  • The cost of maintaining a deep water culture plant is relatively low in the long-run. This is because there are no feeder lines or nozzles involved. There is also no possibility of dealing with clogs in the water pumps either.
  • As there are very few moving parts in the entire setup, it takes very little time to set up, establish, and run a deep water culture farm.

The Drawbacks of Deep Water Culture (DWC)

Here are some of the drawbacks of running a DWC farm:

  • As there are air pumps used continuously in this process, it can be a problem when one of the pumps breaks down.  They will need to be replaced immediately as it has a dire effect on the oxygen levels in the water. 
  • Maintaining the temperature of a non-recirculating DWC system can be difficult in the long run. 
  • When running small systems, the pH levels in the water, as well as the oxygen levels and nutritional supply can tend to fluctuate frequently. A close eye will need to be placed on these levels to keep a check on the health of the plants.
  • If the oxygen supply in the water becomes low, it can kill the plants. This can be one of the biggest disadvantages of these farms and farmers will have to constantly monitor the oxygen levels at all times.

A New Culture of Farming

The traditional methods of farming are falling to the wayside as novel methods emerge to match the demands of the market. Hydroponic farming is indeed a boon to the modern world. Its many subsections such as DWC offer farmers with plenty of alternatives to grow healthy and hearty crops across the year.

DWC is a relatively new form of hydroponic farming, but it is picking up steam quickly because of the ease with which it is possible to set up this system. Information regarding the merits of this system needs to be spread across the farming community to ensure that everyone has access to this form of farming. Solving the global hunger crisis will only be a few short steps away from that point.