How far below the net pot should the nutrient solution be in my cannabis DWC system?

When I operated deep water culture (DWC) systems in my cannabis garden, I kept my nutrient solution about an inch below the bottom of the net basket.

I would advise you to avoid submerging the net basket itself. Anywhere just below the bottom of the net basket is acceptable, as long as the roots are mostly submersed in the nutrient solution. That being said, the most important factor for successful DWC systems is the dissolved oxygen content of the solution. Since the roots are completely submerged in the nutrient solution, the only access they have to oxygen is via dissolved oxygen.

As for having different solution levels in the growing module for vegetative versus flowering stages of growth, this is not necessary if all the parameters of the nutrient solution are in the desired range. The beauty of a DWC system is that everything the plant’s roots need is literally surrounding the root mass. As long as the nutrient concentration, the pH, and the dissolved oxygen content are in check, a DWC system will perform up to its potential.

Benefits of Deep Water Culture (DWC)

Deep water culture is a great high-performance hydroponic system. In fact, when done correctly, there are few growing systems that can rival the speed of growth achieved with DWC. Due to their speed, DWC systems are favorites for gardeners who want to grow big cannabis plants as fast as possible. The accelerated rate of growth is set in motion by the root’s constant access to nutrients, water, and dissolved oxygen. In a DWC system, the plant’s root mass is mostly submerged in the nutrient solution and additional oxygen is delivered via an air pump (or other means).

Dial In Water Temperature & Dissolved Oxygen

Deep water culture systems perform the best when the water temperature is kept between 65-70°F. This is because of the direct relationship between temperature and dissolved oxygen. Generally, the warmer the water temperature, the lower the dissolved oxygen content. When the nutrient solution is kept within the desired range, the plant’s roots have access to adequate dissolved oxygen and the plants will thrive.

Many cannabis hobbyists experiment with DWC because an individual module can be made from a five gallon bucket and a small aquarium pump. For most beginners experimenting with DWC, the major downfall is fluctuating water temperatures. Water temperature fluctuation is unforgivable, especially when the temperature exceeds 75°F. As water gets warmer, it loses its ability to hold dissolved oxygen. This, in turn, leaves a plant’s root mass susceptible to anaerobic pathogens. The best way to ensure success with a DWC system is to monitor and maintain dissolved oxygen.

The dissolved oxygen concentration of a nutrient solution can be measured with a device known as a dissolved oxygen meter. A dissolved oxygen meter will give a reading (in PPM) of the concentration of dissolved oxygen in the solution. A very general rule of thumb for hydroponic gardeners is to try to maintain a dissolved oxygen content of at least 6-9 PPM within the nutrient solution.

Keep on Growing,
Lee G. Lyzit