Deep Water Culture Systems: Pros and Cons

Deep water culture (DWC) is a hydroponic cultivation method in which roots stay submerged in a culture of aerated water and nutrients. As the plants uptake water and absorb nutrients, they also excrete some wastes and the water should be changed as needed, once per week at a minimum. Topping off the water culture with a fresh mix of nutrients will suffice, however, best practices include emptying the old stuff first to replenish the root mass with a fresh mix of water and nutrients. Be sure to adjust pH to a range of 5.6-6.4, depending on the variety being cultivated and stage of growth of the plants.

DWC hydroponic gardeners see a noticeable difference in accelerated growth rate and overall results. When the environment is correctly tuned, DWC systems offer low maintenance, simple low-cost setup, and explosive root growth that supports large plant production. These are great benefits considering it is also a simple method and a great introduction to hydroponics.

Temperature is Key with DWC

With DWC, growers utilize containers full of water to arrange their garden. These containers can be independent and stand alone, or connected in a recirculating deep water culture (RDWC) system. Both scenarios can flood, so proper care needs to be used to prevent damage to property. Keep all electrical cords and connections raised off the floor. Mount them on a wall or hang them — just don’t leave them on the floor where leaks and spills occur. If using an interconnected RDWC system, be sure the connections are properly sealed using gaskets, bulkheads, or other drip-proof plumbing connectors. High summer temperatures can cause problems for any growroom, especially DWC setups where buckets or tubs of water will heat up and become a thermal mass. This will help with heating in winter and work against you in the summer. Winters are more forgiving for DWC, just be sure to maintain water temps above 50°F. If average room temps are kept below 60°F, warm reservoirs further by placing them in a well-lit area, using a lid to keep the light out which will prevent algae and other unwanted growth.

In summer, watch out for root rot, which can occur when water temps remain above 64°F. Pathogens and bad biology thrive in the warmer water. Typically, water temps run about 10 degrees cooler than room temps, so gauge the health of your DWC system by measuring your ambient room temperature. Start with proper growroom heating and cooling. If average temps remain above 75°F, additional cooling may be needed. Consider adding a water chiller to the reservoir if necessary.

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Starting a Deep Water Culture System

Getting started with DWC is perhaps the simplest type of hydroponic setup. All it takes is a bucket, a lid with a hole drilled to fit a net pot, air stones, and an air pump. Place the seedling or rooted cutting (a.k.a. clone) in the net pot with any hydroponic grow medium.

When planting small plants in a medium, hydroponic growers use grow rocks, coco-coir, stonewool cubes, perlite, and yes, even potting soil will work in a pinch. Allow the water level to just barely touch the bottom of the net pot enough to wet the grow medium.

Once roots spread, lower the water level a bit further below the net pot bottom and allow the suspended roots to hang. The upper section of the bucket, although not filled by water, is an extremely humid environment and will form a spider web of root growth to drink the humidity from the air. Strong taproots will grow towards the bottom of the bucket and constantly drink aerated nutrients from the water. With hydroponic nutrients, the elements are chelated with the proper ionic charge for immediate absorption, so the DWC system becomes a nutrient factory on tap which can skyrocket plant growth.

DWC and Environmental Controls

To properly thrive using any grow method, environmental control is key. Keep garden temps between 60-85°F, targeting 70-75°F. This will keep water temps in the correct range for roots and plants to grow vigorously, while keeping away the pathogens and bad biology that can negatively affect them.

Deep water culture and RDWC are important cultivation methods for any hydroponic gardener. Perhaps the oversimplification of these styles is the most useful tool, especially when on a budget or strict timeline. After young plants are allowed a chance to harden in and get used to their environment, root growth will explode in DWC. Be sure to keep a fresh and clean mix of nutrients by changing the water weekly. Leave air stones running in the water culture 24/7, providing roots with plenty of oxygen. This will allow for maximum absorption and faster, stronger plant growth.

Providing these essentials will provide indoor growers with maximum yields for minimal effort. Don’t be intimidated, as this simple method can be setup with ease. Just get going with one stand-alone plant or use DWC or RDWC for your entire garden. Keep the water culture well aerated and maintain a pH between 5.6 and 6.4. Try to keep ambient room temps in a range between 65-80°F. If growing in the correct climate, try using DWC outdoors as well. Whether indoor or outdoor, be sure to top off warm tanks with cold water to prevent potential problems. Enjoy this simple method to learn about and enjoy the benefits hydroponic growing offers.