The Recirculating Deep Water Culture System (RDWC) Guide
Recirculating Deep Water Culture (RDWC) and Deep Water Culture (DWC) hydroponic systems offer scalable, resource-efficient farming solutions - ideal for both novice and advanced growers practicing Controlled Environment Agriculture (CEA).
These soilless systems are used to cultivate plants in grow tents, greenhouses or outdoor environments - providing precise control over water, nutrients, and oxygen.
DWC is a hydroponic method in which plant roots are suspended in a continuously oxygenated nutrient solution that delivers all essential elements directly to the root zone.
This eliminates the need for soil, promotes faster growth, and supports higher yields in a compact, efficient system.
An RDWC system enhances DWC by introducing a circulation pump and large-diameter piping that connects each grow site to a central reservoir, ensuring continuous flow and mixing of the nutrient solution.
This promotes uniform nutrient delivery and oxygenation to each grow site, resulting in healthier root systems and increased plant yields.
What is an RDWC system?
In a Recirculating Deep Water Culture (RDWC) system, plant roots are continuously submerged in an oxygen-rich nutrient solution.
Plants are placed in net pots filled with a suitable growing medium, such as clay pebbles, and suspended from the grow site lids. Clay pebbles support the plant and help retain moisture around the roots.
As the plant grows, it's roots extend into the oxygen-rich nutrient solution. A water pump circulates this solution through interconnected grow sites and a cental reservoir, maintaining consistent water levels throughout the system.
The nutrient solution is added to the central reservoir, where is it is continuously recirculated and oxygenated to nourish all connected plants.
How does a Recirculating DWC hydroponic system work?
Plants require light, water, nutrients, and oxygen to grow - an RDWC system is designed to deliver these essentials with precision.
Oxygen:
Oxygen levels play a critical role in the success of DWC and RDWC systems. Because the roots are submerged continuously, it's essential to use high-quality air stones and an air pump to keep the solution well oxygenated. Air stones create microbubbles that increase dissolved oxygen in the nutrient solution, allowing plant roots to absorb oxygen efficiently. This is essential for healthy root development and overall plant growth.
Water:
RDWC systems conserve water by continuously recirculating the nutrient solution, ensuring that plant roots are always submerged and receive consistent hydration and nutrition. Since warm water holds less oxygen than cool water, it's important to maintain a reservoir temperature between 65°F and 70°F. This range maximizes oxygen retention and supports healthy root development.
Nutrients:
In the absence of soil, RDWC systems rely on a nutrient-rich water solution to deliver essential elements directly to the plant roots. Primary macronutrients—nitrogen (N), phosphorus (P), and potassium (K)—are critical for plant development, along with secondary nutrients like calcium, magnesium, and sulfur. Nutrient requirements vary by plant type and growth stage; for example, leafy greens need a different formula than fruiting crops or cannabis. For detailed guidance, check out our blog on mixing hydroponic nutrients.
In RDWC systems, the nutrient solution is maintained in a central reservoir and circulated throughout the grow sites via a water pump and connecting pipes.
How do you use RDWC?
RDWC systems are ideal for growing a wide range of crops—including cannabis, tomatoes, peppers, cucumbers, and other fruiting or vining plants.
In an RDWC setup, a central reservoir connects to a series of grow buckets via piping. Plants are placed in net pots filled with a growing medium like clay pebbles, which are suspended from the grow site lids.
Air stones and an air pump oxygenate the nutrient solution, which continuously circulates through the system. The water level should be maintained so that it just touches the bottom of the net pots, ensuring root access to both water and oxygen. As the roots extend, the water level can be lowered to 1" to 2" below the bottom of the net pots.
The pump creates a gentle water current that distributes nutrients and oxygen evenly, promoting vigorous root development and maximizing yield potential.
Maintaining proper pH and nutrient concentration is essential for plant health and optimal growth. For example, seedlings require lower nutrient strength (EC), while mature plants need higher levels. pH influences nutrient uptake and should typically be maintained between 5.7 and 6.6. For more information, check out our blog on managing pH in hydroponics
Benefits of a RDWC System
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Conserves water by continuously recirculating and reusing the nutrient solution.
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Delivers a steady supply of nutrients and oxygen to plant roots through continuous circulation.
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Supports faster, healthier growth and higher yields compared to traditional soil-based cultivation.
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Requires less maintenance than many other hydroponic systems. Routine tasks include monitoring pH/EC, topping off the reservoir, and performing water changes every 7–10 days.
Which is better, DWC or RDWC?
Choosing between a DWC and RDWC system depends on your goals, budget, and the level of automation or scalability you need.
Consider the following when deciding which system fits your needs:
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How much time are you willing to spend monitoring and refilling individual buckets?
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Would you prefer the convenience of a central reservoir with weekly top-ups?
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Do your plants require precise and consistent nutrient delivery?
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How much growing space do you have available?
Artisun Technology offers a range of DWC system configurations—from simple single-bucket setups to fully integrated recirculating systems. Here's a breakdown of the most common options:
Individual Buckets (Non-Recirculating):
These standalone systems require manual monitoring and topping off of each bucket. Each bucket includes an air stone connected to a central air pump, but no shared reservoir. Ideal for small grows or hobbyists.
Passive DWC System (Connected Reservoir):
Buckets are connected to a central nutrient reservoir and passively draw solution as plants consume it. Air stones in each bucket provide oxygenation. This setup simplifies nutrient management compared to unconnected buckets.
RDWC System (Recirculating):
This configuration adds a circulation pump that actively moves nutrient solution through the entire system. It ensures consistent water levels, optimal oxygenation, and even nutrient distribution, making it ideal for larger or more demanding grows.
RDWC vs. Dutch bucket
A Dutch Bucket Hydroponic system is typically arranged in rows, with an irrigation line feeding drippers from above and a drainage line returning excess solution to a central reservoir. A pump in the reservoir sends nutrient solution through the drippers, and the runoff drains from each bucket back into the reservoir for reuse.
Siphon elbows in each bucket ensure proper drainage, and the modular design makes the system easy to scale. Dutch bucket systems are ideal for growing vining plants such as tomatoes, peppers, and eggplants. They’re a beginner-friendly option and well-suited for patios or greenhouses.
In Deep Water Culture (DWC) systems, plant roots are suspended in a well-oxygenated nutrient solution. The term “deep” refers to the constant submersion of roots in the water.
Recirculating Deep Water Culture (RDWC) builds on this approach by actively circulating the nutrient solution through all grow sites. This recirculation improves oxygenation, maintains consistent water levels, and ensures even nutrient delivery—resulting in faster growth, healthier roots, and higher yields.
Pre-Made RDWC Kit vs. DIY Setup: Which is Better?
Deciding between a pre-made RDWC kit and a DIY setup depends on your experience level, available time, and growing objectives. Ask yourself:
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Do you have the tools and skills to build a system from scratch?
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How quickly do you want to start growing?
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Are you looking for full customization or a plug-and-play setup?
Pre-Made RDWC Kit
Artisun Technology’s RDWC kits offer a complete out-of-the-box solution, including detailed setup instructions and all components needed to begin growing immediately. No cutting, drilling, gluing, or additional tools required—ideal for growers who want proven performance with minimal setup time.
If you're a hands-on grower and enjoy designing your own systems, Artisun Technology also supplies essential components like square buckets, hydroponic tubing, bulkhead fittings, and more. This approach gives you maximum flexibility to tailor your RDWC system to your specific layout and growing needs.
Materials Required for an RDWC System
To build or operate a Recirculating Deep Water Culture system, you’ll need the following components:
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Buckets / Grow Sites – Containers that hold plants and root systems.
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Reservoir – Central tank for mixing and distributing the nutrient solution.
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Net Pots with Lids – Hold the plants and fit securely into bucket lids.
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Clay Pebbles (Hydroton) – Inert growing media that supports roots while allowing oxygen flow.
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Bulkhead Fittings and Connectors – Ensure watertight plumbing connections between buckets.
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PVC Pipe or Vinyl Tubing – Used to circulate the nutrient solution between grow sites and the reservoir.
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Air Stones – Introduce microbubbles into the water to increase dissolved oxygen.
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Air Pump – Drives air through tubing to the air stones.
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Water Pump – Recirculates the nutrient solution throughout the system.
Preparation Tips:
Before assembling your RDWC system, wash all parts with warm, soapy water and rinse thoroughly. After assembly, slowly fill the system with clean water and check for leaks, tightening fittings as needed. Empty and refill the system before adding nutrients and transplanting your plants.
Common Questions About RDWC Systems
Which plants grow in RDWC?
A wide variety of plants thrive in RDWC systems, including tomatoes, peppers, cucumbers, lettuce, and cannabis. Both leafy greens and fruiting crops benefit from the oxygen-rich root zone and consistent nutrient access.
Do you need an air pump for RDWC?
Yes. An air pump is essential, along with at least one air stone per grow site. Artisun Technology includes one air stone per bucket to maintain optimal dissolved oxygen levels for healthy root development.
How many GPH do you need for RDWC?
For systems with 4–8 buckets, a pump rated between 250–400 GPH is ideal. This ensures even, consistent circulation of the nutrient solution.
How do I change the water in my RDWC?
Use the included drain pump to empty the reservoir. Insert the pump into the reservoir and drain to a sink or container, then refill with fresh nutrient solution.
How often should I change the water?
Change the entire nutrient solution every 7–10 days. In between, top off the reservoir as needed to maintain optimal levels.
What equipment do I need?
See the “Materials Required for an RDWC System” section above for a full list of essential components.
Can roots grow through Hydroton?
Yes. Hydroton (expanded clay pebbles) is an inert, reusable growing medium that allows root penetration while supporting healthy structure and easy transplanting.
Can you overwater in DWC or RDWC?
No—so long as the solution is properly oxygenated. Constant submersion is safe when you maintain appropriate dissolved oxygen, pH, and temperature.
Do I need to flush or inspect the system?
Yes. Flush your system every 7–10 days, and regularly inspect for root overgrowth that could clog pipes or cause overflow.
Explore Related Hydroponic Systems and Components
Whether you're just starting out or expanding your grow setup, Artisun Technology offers a range of systems and accessories to support your hydroponic goals.
Systems
RDWC (Recirculating Deep Water Culture) system
DWC (Deep Water Culture) system
All components are selected for quality, compatibility, and ease of use—ideal for DIY projects or upgrading pre-built systems.