RDWC System Basics – Amp’d-Up Deep Water Culture

RDWC systems are just like traditional DWC systems, except they involve multiple reservoirs that are all connected.

For beginners and hydroponic gardening veterans alike, RDWC systems are one of the most simplistic and successful hydroponic gardening methods.

What is a RDWC system?

RDWC systems consist of a series of reservoirs with grow sites that connect to a central reservoir. The main reservoir houses an air stone and water pump that forces water and oxygen through the system via hoses or tubing. The central reservoir is also where nutrients are introduced to the system.

How do they stack up against a deep water culture system? What are the main differences between the two? Should you opt for a DIY setup or a premade RDWC system?

I’m answering all that and more for you below, so keep reading.

RDWC System Explained – How Do They Work? 

Recirculating deep water culture systems, also known as RDWC systems, are the big brother of the classic deep water culture system, or DWC system.

RDWC systems have a series of containers with grow sites that hold netted pots, growing medium, and plants.

A main container, usually a large bucket or tote, holds the majority of the system’s water, an air supply, and a water pump. 

Nutrients are added to this main water container, often referred to as a reservoir, and then circulate through the system thanks to the water pump. Air also circulates through the system along with the water and nutrients in the same manner.

Each plant in the system soaks up the necessary amount of water, air, and nutrients needed to grow and thrive. The water is then recirculated from each individual container and grow site, back to the main reservoir.

RDWC System Diagram

RDWC vs. DWC

As mentioned above, RDWC is a hydroponic growing method that involves several individual containers. Each container, except the main reservoir, house plants in net pots with their roots dangling in water. 

Water loaded with nutrients and air flow to each container, and after passing through, returns to the main reservoir. It is then oxygenated and continues on a never-ending cycle of recirculation through to feed the plants.

DWC is a much simpler version based on the same principles. A single container acts as the reservoir and the grow site. The container holds an air stone, a grow site with net pot, and the plants’ roots hang down into the water. Nutrients and air are absorbed by the plants along with water. DWC are self-contained and therefore don’t require water pumps.

The biggest difference between DWC and RDWC is that DWC has a single reservoir that also houses the grow site(s). That said, DWC units may have anywhere from 1 grow site to as many as 12.

RDWC works in the exact same fashion, with the addition of a water pump. It is basically a series of individual DWC systems all tied together by a main reservoir. There is no limit to the number of containers and grow sites that an RDWC system can have, aside from the strength of the water pump and how far it can push water.

All things considered, RDWC may be viewed as the superior method because it allows for much larger operations. That means it is capable of producing higher yields than DWC.

Benefits of A RDWC System

RDWC are one of the easiest to use and no-nonsense hydroponic systems out there. Some of the most significant benefits of RDWC systems include:

  • Automated operations
  • Growth acceleration
  • Ease of maintenance
  • Time-saving
  • Consistent operations
  • Produces higher yields
  • Works indoors and outdoors
  • Less of a learning curve involved
  • Isn’t as expensive as other systems
  • Easy to clean

Is a RDWC Kit or DIY Setup Better?

There are two main routes to take once you decide to try RDWC; purchasing a pre-made RDWC kit, or building a DIY system. Both ways you can go have their pros and cons.

An RDWC kit is a sure way to get a properly functioning system up and running on your first try. A DIY approach may be more affordable, and more of a learning experience, but it also requires more time, effort, and patience.

RDWC Kits are among the most affordable pre-made hydroponic grow systems that you can buy. Often, a high-end DIY setup isn’t actually all that much more affordable. Further, if you opt for the cheapest parts available, your DIY setup may malfunction, break-down frequently, or not even work at all.

Only you can be the judge as to whether a pre-made system or building one from scratch is the better option for you. 

DIY RDWC Recommendation

Building a DIY system like the one in this YouTube video recently published by insidehydro is quick and easy.

Below, we go over the entire process, step by step. 

But, first, let’s look at what tools and materials you need to get started:

Tools:

  • Drill with bits
  • Marker
  • Razor knife
  • Measuring tape
  • Rubber cement
  • Sand paper

Materials:

  • Containers (5-gallon buckets or similar size totes work great)
  • Air stone(s) (you can use one in the main reservoir, or one in each container)
  • Water pump (a sump pump or fountain pump works great)
  • Net pots (you can do with or without a growing medium)
  • PVC or vinyl tubing (1 ½ inch to 3 inch is preferred)
  • Air tubing
  • Bulkheads (for connecting the main tubing to each container)
  • “T” connectors (for connecting the air tubing)

Now that you know exactly what you need to get started let’s take a look at the step by step process:

Step by Step Assembly Process:

  1. Mark holes on the side of each container for the bulkheads (low down, just half an inch or so from the bottom)
  2. Drill out the holes, sand them, and insert bulkheads (this is where the PVC or vinyl tubing connects)
  3. Drill 1/4th inch holes in the top of each bucket and sand them until smooth (rough edges may put holes in the air lines)
  4. Measure the distances between each container and cut your tubing and air lines to fit properly (the razor knife should work, however, you may need a saw or cutters depending on the material)
  5. Connect main tubes from the main reservoir around to each container, one by one (use rubber cement if needed)
  6. Insert water pump into the main reservoir and connect hoses or tubing
  7. Place air stone into the main reservoir and run air line from container to container
  8. If you have wide-lip net pots, place them into each container (and insert growing medium if desired)
  9. If you are using containers with lids, trace the bottom of your netted pots in the center and use the razor knife to cut proper holes to sit them in (and fill with a medium if you prefer)

Finishing Touches:

After following the steps above, you’re ready to fill your system up with water and give it a test run. Start by adding a little water at a time. That way, if there are problem areas, you don’t have an enormous leaky mess on your hands. 

Also, after your test run, empty out the water and fill it up again before adding your plants. This helps ensure that no harmful residue from the containers, rubber cement, or other unseen contaminants from poisoning your plants.

An important note: Avoid over tightening the bulkheads and other connectors as it may result in cracking containers, leaks, and eventual system malfunction. Also, avoid leaving gaps in the top of the containers that allow light to shine directly down into the hydroponic water as it causes unwanted algae to grow.

Pre-Made Kit Recommendations

Root Box Hydroponics Grow 2 System Current Recirculating Deep Water Culture RDWC

The Root Box Hydroponics Grow 2 System is a recirculating deep water culture kit that comes with all the basics. From 12-gallon containers and a 5-gallon controller to air pump and water pump, everything you need to get started with RDWC hydroponics is included.

The system is quick and easy to install, energy-efficient, space-saving, and built with high-end components meant to last. It fits inside of a 4ft by 4ft grow tent or open space inside your home, office, garage, or basement.

Check Price On Amazon

Pros

  • 594GPH air pump
  • 660GPH waterfall pump
  • 6 air stones
  • Float valve
  • Space efficient
  • Easy to maintain

Cons

  • There are only two grow sites
  • Lights are not included with the kit

 

DasMarine Deep Water Culture Hydroponic Bucket Kit

If you’re looking for a set up with more than two grow sites, the DasMarine Deep Water Culture Hydroponic Bucket Kit is a sure bet. The kit includes everything needed for growing four massive plants and is made by a manufacturer with a growing reputation in the world of hydroponic gardening.

This kit includes four grow sites and a fifth container that acts as a controller for the others. It’s easy to assemble and works for growing just about any size or type of plant imaginable. It also includes a growing medium, which most kits lack.

Check Price On Amazon

Pros

  • Complete kit
  • Grow sites have lids and growing medium
  • Easy to put together and use
  • Works for all plants

Cons

  • Each container has only one grow site
  • There are no lights included with the kit

Root Box Hydroponics Grow 4 System Current Recirculating Deep Water Culture RDWC

The Root Box Hydroponics Grow 4 System is also an excellent choice for those searching for a slightly larger set up. Similar to the Grow 2 System, the package includes everything you need to get up and running as quickly as possible.

The only real difference is that this system comes with a stronger water pump, a more powerful air pump, and four more air lines in addition to two extra containers with grow sites.

All of the parts to this system are high-quality and durable. You won’t need to replace anything for quite some time. That said, it does take up a bit more space than its smaller version. The system fits inside of a 5ft wide and 6ft long area or grow tent.

Check Price On Amazon

Pros

  • 800GPH waterfall pump
  • 950GPH air stone
  • 4 10-inch net pot lid baskets
  • 4 12-gallon low profile reservoirs
  • Quick installation
  • Very easy to run and maintain

Cons

  • Isn’t designed for outdoor use
  • Doesn’t include lights
  • Uses a bit more energy than the Grow 2 version

Common Questions About RDWC Systems

Do you need an air pump for RDWC?

RDWC systems require at least a single air pump and air stone in the main reservoir. Some hydroponic gardeners, however, prefer to add an airstone to each individual container with grow sites.

How many GPH do you need for RDWC?

Many experienced hydroponic gardeners recommend running between 800 and 1200 GPH through RDWC systems. That said, for each individual container in an RDWC system, a minimum of approximately 80 GPH of water is required for healthy and thriving plants.

Closing Thoughts About RDWC Systems

RDWC systems are excellent for hydroponic gardens of all shapes and sizes. They work indoors and outdoors, and are capable of growing just about any sort of fruits, vegetables, herbs, flowers, or houseplants that exist.

Whether you’re interested in upgrading your current DWC system to something larger, or are just getting started with hydroponic grow systems, you can’t go wrong with an RDWC system if you plan to grow several plants at a time and are looking for large yields.