Deep Water Culture

A deep water culture is one of the simplest and most effective hydroponic systems. In this design each plant grows over a large (and deep) reservoir. The roots dangle into the nutrient solution in the reservoir below.

This is one of the simplest designs that you can build at home. A mason jar filled with seeds or one 5-gallon bucket with a small air pump will get you started!

There are three main parts to this system:

  1. In a DWC, the plant rests over a sealed bucket in a net basket.
  2. The bucket holds a solution of water and nutrients. The addition of an air pump and air stone keeps the nutrient solution aerated. It is important to keep the solution aerated so that the roots get enough oxygen.
  3. Instead of using soil to give the roots structure, an inert growing medium such as expanded clay pellets, or rock wool gives the roots a sturdy base.
Deep Water Culture

Nutrient Solution

All plants need a fertile foundation to thrive. In the traditional farm or garden setting, plants get their nutrients from soil that can contain additives such as compost, manure, or chemical fertilizers. Again, hydroponics is completely soil free, so nutrients are delivered directly to the plants through the solution with which they are watered.

The three main ingredients:

  • Oxygen: In a deep water culture the roots remain submerged in nutrient solution. Since the roots stay submerged in the solution, instead of the traditional oxygen-rich soil, the roots can “drown”. Aerating the roots using the air pump and stone improves plants’ absorption of oxygen. If an air pump is not available, regularly changing out the nutrient solution will help expose the roots to air.
  • Water: Sterile water supplies a cleaner nutrient solution. We do not recommend using tap water in the deep water culture system as it can hold many unwanted particles that can infect the plants. Distilled water is the most effective choice. Though, if a water filter is available to you, then that would cut the use of the plastic bottles associated with buying distilled.
  • Supplements: A superior quality soil holds all the micro and macronutrients necessary. Because we have no soil, we need to use supplements such as nitrogen, potassium, and the other nutrients plants need. You can buy or mix your own supplement and there is no need for fertilizer.

Calibrating the nutrient solution increases plant growth. The pH and electrical conductivity (EC) of the water fluctuate as the plant grows and consumes nutrients. For this reason, keeping consistent tabs on the nutrient solution ensures that it stays in the best range of the crop. The deep water culture system makes the replacement of the nutrient solution simple and minimal. Simply drain and re-fill.

Recirculating Deep Water Culture

Single DWC buckets are difficult to maintain as production is scaled up. As a result, this has led to the creation of Recirculating Deep Water Culture (RDWC) systems. An RDWC features individual buckets for each plant interconnected with series of PVC pipe. A separate control bucket holds the bulk of the nutrient solution. This allows the operator to test for pH and EC at an individual location for multiple plants. To aerate the nutrients, a pump pulls water from the rear of the system into the control bucket and may cycle through several times.

Recirculating Deep Water Culture System Diagram

Moreover, RDWC can be customized in several different formats depending on the number of individual buckets and space provided. It saves time and supports a consistent nutrient solution for many plants.

Potential Issues

It is not all sunshine and roses. There are some issues with a deep water culture system that can cause problems, but they are all avoidable if maintenance is consistent.

  • pH, water level, and nutrient concentration will be in contant flux.
  • Roots will suffocate in a low-oxygen nutrient solution, especially if there is an electricity outage or a pump failure.
  • It can be difficult to support a consistent water temperature but adding a thermometer can help keep track of fluctuations.
  • Potential issues with the system stem from a lack of understanding of how to keep it clean or allowing the solution to get too warm.

Why you should use Deep Water Culture?

All said, the positive benefits outweigh the issues. A deep water culture system is easy to assemble and versatile with styles ranging from counter-top systems to larger set-ups for commercialization. The expedient nature of growth offers quicker harvest times as well as the ability to produce all year long.

Do not let the simplicity of this design fool you. We have grown large tomato plants in a simple 5-gallon bucket.