Hydroponics 101: Introduction to Deep Water Culture for Cannabis

For beginners curious about hydroponics, deep water culture (or DWC) is the simplest and most affordable choice. The easiest DWC systems use equipment that is readily available online hydroponics shops, like Happy Hydro. It's a perfect introduction to the world of hydroponics, and one many growers prefer for an at-home setup.

A slightly more sophisticated set up is called the recirculating deep water culture or RDWC. Once you've accomplished a single reservoir, you graduate to the RDWC system, which moves water through three or more individual containers. Of course, it requires a bit more time and financial investment but is adaptable to larger operations and custom grow spaces.


The Basics of a Deep Water Culture System

As with all hydroponics systems, the DWC system is an indoor grow system which replaces soil with a growing medium and submerges the root system into a nutrient-rich water reservoir. 

First, let's break down the most basic deep water culture system. It requires the following materials:

A single reservoir system can be as simple as a five to seven-gallon bucket or a large Rubbermaid Tupperware container. Once you've filled the reservoir bucket with water, the net pots are settled securely into the lid. Outside this reservoir, you'll set up the air pump connected with tubing running to an air stone set inside the reservoir. 

An air pump and air stone are critical components within this system because plant roots need air to breathe. There are pockets of oxygen in between the soil particles, but there is little to no oxygen in stagnant water. If you fail to aerate your system, the roots would absorb all the original oxygen and eventually drown. 

Although you can grow several plants within a single reservoir, most growers prefer to place one plant per bucket into a larger multi bucket system. This is because individual buckets allow for multi-strain grows. It allows you to move each plant out of a veg room and into flower as needed. 

These multi-bucket systems are classified as a recirculating deep water culture system, which expands the techniques used within the basic DWC system. It is a single primary reservoir, connected with piping to two or more reservoirs containing plants. This system requires the same basic components as the simple DWC setup, with the addition of a water pump and a series of pipes connecting all the buckets together. 

The pump pushes water through the system to circulate through each bucket and eventually back into the primary reservoir. You add nutrients to this primary reservoir. 

Find out more about how to get the most out of your deep water system here. 

How to Build a Recirculating Deep Water Culture System

  1. Determine Layout: Whether you are working with a single reservoir or many, plan each plant's placement and build the system around that. Recirculating DWC systems are typically placed in a long line, in a circular loop, or along a main "stem" with each bucket connected as a "branch" to each side. Draw it out with detailed measurements.
  2. Buckets and Pipes: Take a trip to the hardware store with your DWC system map in hand. You'll need one bucket for each plant and an additional bucket for the main reservoir. Most growers stick with five to seven-gallon buckets and 1.5" to 2" PVC pipe (vinyl will also work). Based on the pipe size, you'll also need bulkheads or another pumping connection to bring it all together.
    1. Important: Choose opaque piping and reservoirs wherever possible to reduce the risk of algae build-up within the system. 
  3. Water Pump Calculation: Calculate the total capacity of your DWC system and multiple by seven. At the very least, you'll want a water pump capable of moving the water through the buckets seven times per hour. For example, a 25-gallon system will require a water pump rated at 175 gallons per hour.
  4. Air Stones and Air Pump: There are two options for airstone placement: one per plant (bucket) or one within the main reservoir. As for the air pump, you'll need one with double the system's capacity for best results. For example, if you have a 25-gallon system, look for an air pump with at least a 50 gallon per hour capacity.
  5. Connect the Dots: Using your map as a guide, build the system in place. When the time comes, you can move the net pots with the plant from veg to flower rooms, but the reservoirs stay as-is. Cut holes into the reservoir lids to place the net pots and fill with an inert growing medium with low water retention, perlite, clay pellets, or lava rocks.
  6. Test, Test, Test: Once complete, fill with water and nutrient solutions, then allow the system to run for several days without placing any plants inside. This will work out any kinks in the system, and most importantly, allow the pH to even out. If you have questions about pH within your hydroponic systems, we've gone into much more detail here.

A More Refined Indoor Grow with a DWC Hydroponic System

Cannabis cultivators move to hydroponics for the control it gives them over the final results. With careful tinkering, you can produce more quantity, in higher quality. 

Deep water culture is the perfect entry point into the world of hydroponics because it's simple, affordable to build at home, and adaptable to any size grow room. 



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