It’s Time For A Hydroponic Deep Dive – Mastering DWC & RDWC

Deep Water Culture (DWC), known as Deep Flow Technique, is one of the world’s most popular hydroponic growing methods. This particular approach to hydroponics was invented in the late 1990s by grower, ‘Snype ’who needed a way to feed his crop while travelling. Snype revised his original system twelve years later, and Recirculating Deep Water Culture (RDWC) was born. In today’s newsletter, we will give you the rundown on these revolutionary growing methods, explaining what they are and what makes them unique. 

Let’s start with Deep Water Culture (DWC) 

There is no shortage of DWC systems on the market today; some feature floating rafts that hold many plants at once, while others have space for only a single plant, usually grown in a bucket/reservoir with a net pot. 

Net pots are filled with the grower’s choice of media (typically expanded clay), while the attached reservoir is filled with a nutrient-rich water solution. 

As the plant grows, the roots stretch through the media and net pot, immersing themselves in the hydroponic solution below. Because this nutrient solution is not oxygenated, an airstone connected to an air pump is added to the reservoir. 

It’s important to remember that when using a growing method like DWC, the pH and EC of the connected nutrient solution will fluctuate. Because of this, growers must regularly check and adjust the pH of their reservoir to ensure optimal nutrient uptake. 

The best way to do this is to purchase an EC pen, pH pen and our pH starter kit, which has everything you need to monitor and optimise your nutrient solution. 

Another important consideration when growing by way of DWC or its variants is water temperature. If the water in your reservoir is too hot, you’ll limit the amount of dissolved oxygen in it, increasing the risk of fungal infections like root rot. If the water in your reservoir is too cold, you’ll stunt plant growth and yield size. 

Ideally, the temperature of the water in your reservoir should sit between 18 – 22 degrees Celsius. 

Depending on your set-up, you can cool your system by cooling either your internal or external environment. For example, an indoor grower may use an air conditioner to cool their grow, while an outdoor grower might make use of a water chiller or even add an ice pack directly to their reservoir instead. 

When it comes to heating, adding a water heater directly to the reservoir is preferred.

A Deep Water Culture system is one of the most straightforward hydroponic setups on the market, making it more affordable than many alternatives. DWC is easy to expand for growers cultivating multiple species of plants or the same species of plant in different growth stages. Additionally, in DWC, if a plant suddenly develops a disease or fungus, other plants are not infected, mitigating the spread and severity of the problem. 

Conversely, managing multiple DWC systems can be very time-consuming, as each reservoir must be handled individually. If you’re growing many plants at once, it may make sense to automate this process, saving significant time and effort and ensuring a more consistent result. 

Enter Recirculating Deep Water Culture, a variant of DWC that does just that. 

Like DWC, plants grown using RDWC utilise expanded clay-filled net pots connected to reservoirs filled with nutrient-rich, oxygenated hydroponic solution. The difference in RDWC is that each of these smaller reservoirs is connected to one big, centralised reservoir. 

This centralised reservoir houses the grower’s air pump, which uses an air stone to force oxygen through the entire system using interconnected tubing. As needed, growers will add their nutrients and pH up-and-down agents to this main reservoir.

This means that instead of managing multiple reservoirs individually, the grower can manage a single reservoir shared by all their plants. 

When utilising RDWC as a growing method, it is strongly recommended that a grower’s nutrient solution is replaced entirely every 14-21 days.

To carry out this process, simply drain your reservoirs of nutrient solution before refilling with hydrogen peroxide and water. Always follow the manufacturer’s dosage instructions carefully when flushing out your system. 

Soak your system and plant roots in the solution, gently running your hands over the surface of the reservoir and plant roots to clean and sterilise them properly. 

Discard the cleaning mixture once your system is sterile and replace it with a fresh hydroponic nutrient solution. 

This process reduces the chance of fungal infections like root rot and leads to healthier plants, bigger yields, and a much easier cleanup after your grow is finished. In RDWC, this is especially important as a grower’s nutrient solution cycles through every plant in their system, increasing the speed and spread of infection if it occurs.  

There are advantages and disadvantages to both DWC and RDWC. 

While DWC offers affordability, simplicity and easy maintenance for beginner growers, it can take longer to maintain, especially as growers scale up the size and complexity of their operation. 

On the other hand, RDWC automates the process of managing hydroponic crops, making growing quicker but increasing the risk and severity of pathogens entering their system.  

If you want to try growing your fresh fruits or veggies using Deep Water Culture or Recirculating Deep Water Culture, we have linked our favourite systems at the end of this newsletter. 

If you would like more information about Deep Water Culture and which of its variations is right for your crop and growing space, call 1800 640 222 or visit us in-store. 

Thanks as always for reading, and until next time, happy growing!