How To Build A Recirculating DWC System (What To Know)

You can build a recirculating DWC by mimicking the traditional DWC and adding a few modifications. With the added concept of piping that circulates the nutrient-rich solution, your new recirculating DWC will produce a bigger-scale hydroponic system.

 If you are looking to scale your deep water culture system or you are looking to start your hydroponic garden, look no further than the recirculating DWC. 

This brief article will go over what you need to build your recirculating DWC system and the many benefits it has to offer. 

What Is A Recirculating Deep Water Culture System?

A recirculating deep water culture system, also known as a recirculating DWC system, is similar to a deep water culture system (DWC). They both have the roots of the plants submerged in a nutrient and oxygen-rich solution 24/7. 

The main difference between the two is that in a recirculating deep water culture system, the solution gets recirculated and pushed through the buckets before returning to the reservoir. 

In a traditional deep water culture system, the water stays in that same bucket; it does not move anywhere else. 

This recirculating deep water culture system is also very similar to the ebb and flow concept. The significant difference between the two is that water is drenched and drained in intervals in the ebb and flow system. 

In contrast, the water is reused in the recirculating deep water culture system and does not get drained unless you are cleaning out the system.

How Does A Recirculating DWC Work?

A recirculating DWC is a hybrid version of a traditional DWC and a flood and drain system minus the draining part. 

Three main components are vital to this system: 

  • Oxygen. Because the roots are submerged in water, the water needs to be well oxygenated. This problem is solved with the air pump and air stone you will use in the reservoir. 
  • Water. Compared to traditional farming, where you have to water your plants consistently, hydroponic systems eliminate that need. The plants are already submerged in oxygen-rich water, so they are constantly being provided with the perfect amount of air and water. 
  • Nutrients. Typical soil usually contains the necessary nutrients that your plants need to grow and thrive. In a hydroponic environment where there is no soil, you need to make sure that your system has adequate nutrients infused in the water so that the plants can thrive and grow to their fullest potential. 

 In this system, the nutrient-rich solution originates from the reservoir and pushes through piping to each connected tank instead of sitting in just one tank. 

This hydroponic system is preferred over the traditional DWC because you can quickly scale the recirculating DWC. Several containers are connected to a reservoir that pushes the water through, and if you need more room, you can add additional containers to scale to whatever size you need. 

If you decide to add more containers, it is essential to remember that you will need to add additional nutrients to the reservoir to make sure that each plant receives the proper amount needed to grow. 

For your system to work correctly and your plants to thrive, it is recommended to have no more than three plants in each container. Too many plants in a container can risk each plant not receiving the proper amount of oxygen needed to survive. 

What Will You Need To Build Your Own Recirculating DWC system?

  • A reservoir to hold the nutrient-rich water
  • Large air pump and air stone
  • Inline water pump
  • Tubing for each bucket 
  • Net pots for each plant
  • Growing medium of your choice
  • pH meter and kits 
  • PPM meter
  • Hydroponic nutrients
  • Multiple dark-colored containers or buckets 

It is extremely important to make sure that you purchase a dark-colored bucket because any clear or light-colored containers will let in light that can change the temperature of the water. 

How To Build A Recirculating DWC System

A recirculating DWC has the same principles as a traditional DWC, with the added concept of pipes being attached to the buckets to push water through.

There are already pre-built recirculating DWC systems that you can purchase online. If you want to personalize and build your own recirculating DWC, you can also do so with the listed items above. 

To build your recirculating DWC system, follow the steps below.

Set Up Your Reservoir

Designate one of your containers to be your reservoir where the nutrient-rich water will be stationed. Inside of the reservoir, set up and attach the inline water pump. You need to have an air stone and air pump in the large tank.

Prepare Each Container

Once you have decided on how many containers you want to have in your system, cut out holes on each side of the container and attach the piping, ensuring that they all connect back to the reservoir. Make sure also to put an air stone in each container.

Set Up Your Plants

Each plant that you put in the container needs to be in its own net pot. Net pots are unique pots with a wide mesh bottom, allowing the plant’s roots to reach the water in the container. 

If you cannot purchase net pots, you can buy regular plastic pots and make large holes in the bottom so that the roots have room to reach down into the water. 

After you place your plant in the pot, fill the pot with your growing medium of choice. Most growers like to use perlite or clay pellets.

Some plants grow better with other mediums to check what works best with what you are trying to grow. 

Balance The pH

Each plant needs different types of pH levels to grow correctly. The average plant needs something between 5.5-6.5.

You can shoot to have the tank at about a level of 5.8, but you should always make sure that you check what pH your plants need because some need it to be higher or lower than average.

What Are Some Problems Associated With A Recirculating DWC?

The main problem with recirculating DWC is the buildup of biofilm. Biofilm typically forms at the surface of the water, but it can also coat the side of your reservoir, and you may not see it due to the darker containers used in this system. 

If it is not caught early, the slimy film can easily clog the pump and pipes, restricting the water flow needed to keep your plants alive.

It also can cause the pH levels to rise, which can also cause crop loss. When you check your system and notice a pungent mildewy scent, you may have biofilm and other microorganisms growing in your tanks.

Make sure to check the reservoir and each tank to mitigate the growth. 

Clogged Pipes

The recirculating deep water culture system contains a complicated pipe network that increases the chance of pipes being clogged. 

Dead roots may fall off the plants without you knowing, and they can clog the pipes. 

Waterborne Diseases

Although it may seem like a great idea to create a recirculating deep water culture system because you can grow several more plants at once, you run the risk of easily transmitting waterborne disease. 

In a traditional deep water culture system, you can quickly drain that one container and mitigate your damages if a plant becomes infected. 

In a recirculating DWC, you have several tanks connected to one reservoir that just continually pushed the nutrients around, so it may be hard to find out where the original problem started.

 You also run into having to drain and clean out each tank or having to dispose of all your plants because of the probable mass contamination. 

Limited Variety Of Plants

Different varieties of plants, vegetables, and fruits all require different PPM, EC, and pH levels to grow correctly. With the recirculating deep water culture, you are limited to only growing plants with similar ppm and pH requirements. 

Another issue is that you can only grow certain plants that aren’t slow-growing or too heavy for your system to hold up.

It is also important to note that you probably don’t want to grow any plants with long and complicated root systems as they can clog the pipes and take up most of the nutrients away from other plants in the system. 

Electric Outages

Electric outages or pump failures can also cause enormous problems for your hydroponic system. For this system to be successful, the constant oxygenation of the water is essential.

If your power were to go out or your pump fails, it can cause your plants to die due to oxygen starvation. 

Water Quality

The temperature and quality of your water are very vital to your plant’s success. If the water is too hot or too cold, it can stunt the growth of your crops.

is also essential to monitor the temperature of the room. If your growing zone’s temperature rises above 70 degrees Fahrenheit, it can have a significant impact on your crops. 

It would be best to monitor recirculating deep water culture systems for temperature because of the added heat from the water pump, lighting, and room temperatures. If this is not well maintained, this can expose your crops to potential root disease. 

You will need to regularly check your water’s quality to ensure that no factors impede the nutrients that need to be passed through.

Hard water, pathogens, or too much alkalinity can play factors in how your plants absorb their nutrients. 

Pathogens

As mentioned above, pathogens can hurt your plant’s way of getting the nutrients needed to grow properly. Pathogens can come from contaminated plants, an unclean environment, and insects.

Ensure to monitor your environment’s cleanliness and sanitize any containers or tanks you use before starting your hydroponic system. 

Pathogens can make their way into your tank from unclean floors and unkept containers. Bleach and water are good enough to clean away any pathogens. 

Algae

Algae usually form when there is too much phosphorous in a nutrient solution and too much lighting. Algae multiply when there is light involved, so make sure you purchase containers that block out light.  

Algae may not seem like something terrible in your hydroponic system because algae produce oxygen in daylight conditions, but algae can be extremely harmful.

When it is dark, algae depletes oxygen which can throw off your container’s pH balance. Also, be mindful of the growing medium that you are using as Rockwool can attract algal growth. 

Sanitation

Sanitizing your recirculating deep water culture system can be a hassle. It can be time-consuming because multiple large containers are involved, and piping that needs to be thoroughly cleaned.

When you are flushing out the system, make sure that you clean and sanitize everything in the system to prevent cross-contamination and any future problems with your plants. 

To ensure that everything in the system is thoroughly cleaned, use fresh water and bleach when soaking the pipes and containers. 

If you do not have floor drains in your growing zone, you can siphon the water out from each container with sump pumps and dispose of the water properly away from any other hydroponic systems. 

Types Of Water To Use 

Public Utility Water

Most tap water originates from a public utility center if you live in the city or the suburbs. These centers typically treat the water to kill off any microbes or diseases that can cause illnesses in humans. 

When they treat the water, they usually use chlorine and other chemicals, which can alter the pH level in the water. 

If you live in a more rural area, you most likely obtain your water from underground wells. Inside of those wells is a plethora of minerals that alter the pH level of the water. Minerals, like calcium, can cause white buildup around your pipes, which can lead to clogs. 

Make sure that you test and treat your water as needed before putting it in your hydroponic system to ensure that they have the proper pH required to absorb nutrients. 

Distilled

The best type of water to use in your recirculating deep water culture system is distilled water because it is already pH neutral. Distilled water is created by turning tap water, or any type of water, into steam. You will then collect the condensation, and you can use it in your systems.

This process purifies the water, removing any bacteria, heavy metals, or chemicals that may have been in your tap water or other water sources. 

If you can’t distill your water before putting it into your system, you can always purchase distilled water bottles. 

Filtered

Filtered water is also another great source of water to use for your hydroponic system. If you are choosing to filter your tap water, it is best to use simple carbon-based filters.

You can also use a more complex reverse-osmosis system if you choose to. Regardless of which method you choose, you will still end up with nearly pure water. 

What Are The Benefits Of A Recirculating DWC

  • Reduced water use as water is recycled
  • Nutrient solution and oxygen is constantly circulating
  • Plant growth is faster; some plants grow in half the time than they would if you planted them in soil.
  • Not as many nutrients or fertilizers are required because the plants are submerged in nutrient-rich water.

Lighting For The Recirculating DWC

If your system is held in an area where there is natural sunlight, then the light and heat from the sun should suffice. 

If you are running your system indoors, you can set up lights, but you should be mindful of the light’s heat. Try to search for light bulbs like T5 fluorescents known to run a bit cooler than the average light bulb.

Carbon Filters and UV Lines 

For your recirculating DWC hydroponic system to work best, your plants need to have an uninterrupted flow of nutrients. Microorganisms and diseases are the biggest problems that can halt the growth of your fruits and vegetables. 

To help solve this problem, you can install carbon filters and inline UV filters to ensure that the nutrient-rich solution stays untainted.

The primary purpose of the carbon filter is to remove any plant exudates. Plant exudates are plant hormones that attract microorganisms. 

What Nutrients Are Best For My Recirculating DWC system?

It may be tempting to purchase nutrients and fertilizers that may work best for the in-ground type of plants and farming, but they most likely won’t work as well as it needs for your system.

These types of nutrients tend to get stuck in pumps, and they may clog up your system. When picking nutrients for your plants, stick to those that are specifically made for hydroponic setups. 

The best thing about nutrients in your recirculating DWC is that you don’t need to put too many nutrients in the system since they are being pushed through and shared between the plants. 

How Deep Do I Submerge My Plant?

When putting your plants into the containers, it is important not to submerge the entire plant. Ensure that you only dip the bare root of the plant into the water as the plant’s stem should be above water. 

A good rule of thumb is to have about two inches of the root above the water, as this helps with oxygen intake. 

 If you submerge the entire root, you will run the risk of drowning your plants or slowing your plant’s growth. 

What Plants Work Best In A Recirculating Deep Water Culture System?

Lettuce

  • Looseleaf
  • Butterhead
  • Romaine

Tomato

  • Beefsteak
  • Cherry tomatoes
  • Brandywine
  • Super Sweet 100

Peppers

  • California Wonder
  • Vidi
  • Yolo Wonder

Other Leafy Greens

  • Sorrel
  • Kale
  • Spinach
  • Bok Choy
  • Swiss Chard

Herbs

  • Basil
  • Dill
  • Thyme
  • Cilantro

What Temperature Should The Reservoir Water Be?

The temperature of the water in your system can make or break your plant’s growth. If your water is too cold, you can stunt the growth of your plant. Water that is too hot can run the risk of decreasing the oxygen level. 

The ideal temperature for the water should be about 65 degrees Fahrenheit.

When Should I Change My Nutrient Solution?

Three weeks is a reasonable amount of time in between changing out your nutrient solution. Of course, that time frame can be sooner or later, depending on your growing plants. 

Other factors that can affect when you should change your solution are:

  • Your reservoir size
  • The stage of growth that your plants are in

If you don’t want to do a complete change, you can always add more water into the reservoir with some nutrient solution, but that may not be easy to find the right balance. 

It is better to do a complete change to avoid playing a guessing game about the right balance between the solution and water. 

How Can I Measure The Oxygen Level In My Nutrient Solution?

You can purchase oxygen meters to measure the amount of oxygen in your solution, but it is unnecessary. 

You can continuously monitor your air pump, check the pH levels, EC levels, and temperature. As long as those are up to par, you should not have to worry about the oxygen level in your containers. 

Is Sterilizing My Container Necessary?

Sterilizing your container is something that many hydroponic garners debate because of the pros and cons. 

With a sterilized container, you may lose out on the beneficial bacteria that can grow in your container and help your plants grow. 

If you choose not to sterilize your container, you can get beneficial bacteria in your system. It is important to note that allowing these beneficial bacteria in can also run the risk of inviting other organisms that may damage your plants or throw off the pH levels of your water. 

PPM/EC Adjustments

It is essential to monitor the PPM and EC of the nutrient solution to ensure that your plants grow to their fullest potential. Fluctuations are likely with the recirculating DWC, and those fluctuations can cause deficiencies which can lead to your plants becoming stressed or dying. 

It is ideal to check the PPM and EC levels each time you change out the solution.

Bottom Line

The recirculating deep water culture system is an upgraded version of the traditional deep water culture system, bringing you higher crop yields. Once you have the system set up and running, you can expect healthy and quick growth. 

This system does not require too much maintenance, but you still want to do your due diligence to ensure that everything is working as it should. 

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