What is a Deep Water Culture System?
In a deep water culture (DWC) hydroponic system, plant roots are fully submerged in a nutrient solution. They manage to survive this way because of one key element: the addition of dissolved oxygen to the root zone. For growers new to hydroponics, DWC systems are among the easiest systems to set up, requiring just a few materials and tools you might have lying around the house already.
Standard water culture systems and deep water culture systems (DWC) are about the simplest types of hydroponic systems available, and they are also very efficient at growing plants hydroponically.
Both hobby and commercial growers use this type of system, mainly because they are simple and inexpensive to build. Best of all, there are plenty of imaginative ways to use and build water culture systems out of different materials.
What You’ll Need for a DWC Hydro System
- Container/reservoir to hold the nutrient solution
- Aquarium air pump
- Air line/hose
- Air stones (or soaker hose) to create small bubbles
- Baskets, pots or cups to hold the plants
- Some type of growing media
How It Works
In a water culture system, plants are suspended in baskets right above the nutrient solution in the reservoir, usually by Styrofoam floating on top, or through holes cut in the lid covering the reservoir. The roots hang down from the baskets directly into the nutrient solution, where they remain submerged 24/7. The reason they don’t suffocate is because they get the air and oxygen they need from air bubbles rising through the nutrient solution, as well as from dissolved oxygen in the water itself.
In a water culture system, the more air bubbles the better. There should be enough rising bubbles to make the water look like it’s boiling at a heavy, rolling boil. The bubbles should be rising up through, and making direct contact with, the roots as they rise to the top of the water to be most effective for the plants. There are two ways of providing aeration and dissolved oxygen to the nutrient solution: air bubbles or falling water.
Air Bubbles: An aquarium air pump and air stones are typically used to provide air bubbles to the nutrient solution for water culture systems, as well as other types of hydroponic systems. The air pump provides the air volume, and is connected to air stones with an air line/tubing. The air stones are made of a porous, rock-like material; the small pores create small individual air bubbles that rise to the top of the nutrient solution.
A soaker hose, which creates even smaller bubbles, can be used in place of air stones as well. The smaller the air bubbles, the better they are for aerating nutrient solutions, as smaller air bubbles provide more contact surface with the water. The contact between the air bubbles and water helps replace the dissolved oxygen taken up by the plants’ roots.
Falling Water: Though not typical in at-home water culture systems, surface agitation from falling water splashing around is another good way of aerating the nutrient solution. The higher the water is falling from, and the more volume of water falling, the more downward force it has when it hits the water’s surface. The more downward force, the deeper the agitation and the more dissolved oxygen provided. This method of aeration is more common in commercial water culture systems because they use larger volumes of water than what home growers use.
Recirculating Water Culture Systems
Another variation of the typical water culture system is a recirculating water culture system. The recirculating system works like a flood and drain system, but it never drains. You can have as many growing containers (reservoirs) as you want connected to one central reservoir. Each growing container has its own fill line, as well as a drain/overflow tube that drains back to the central reservoir.
Some growers use buckets instead of wide, shallow containers. Each bucket has its own plant in it and is filled with nutrient solution. A lot of systems feature a row of these buckets and use a fountain/pond pump to pump the nutrient solution up to each of the buckets. As the water fills the buckets, the excess water spills over into the overflow tube and flows back to the reservoir, where it’s recirculated back through the system again.
Most growers who recirculate the nutrient solution like this in their water culture systems only use an air pump in the central reservoir, rather than in each individual bucket, to save money. They also let the water pump run 24/7. However, if you have air bubbles running in each bucket, you can vary the ON time for the water pump, and the plants will benefit from having direct contact with the rising air bubbles contacting the roots.
Recirculating the water allows you to use falling water as a source of aeration in the system. You also won’t need to keep checking the water level in each container to replace the water the plants drank up—you just check and replace it in the central reservoir. This is a nice benefit when you are growing large plants, or many plants in the same system. In fact, just about all of the large, commercially operated water culture systems recirculate water through the system.
For more information on building and maintaining a water culture hydroponic system, visit homehydrosystems.com for your free, downloadable plans.
Source: Home Hydro Systems
Written by Jeff Sanders