Deep Water Culture For Plants: How To Build A Deep Water Culture

What is Deep Water Culture?
Deep Water Culture, otherwise known as Direct Water Culture or DWC, is a simple yet effective hydroponics system that works by suspending the plants’ roots directly into a highly oxygenated nutrient solution. DWC systems are proven to be very effective, easy to construct and operate, and are an ideal choice for those of you who are new to hydroponic cultivation.

Other Hydroponic Systems you should consider
Aeroponics - This is the process of growing marijuana in an air or mist environment however without using soil or any kind of medium.
Continuous flow – Continuous flow techniques include NFT and Drip systems. The basic concept is a continuous flow of nutrients with good drainage and flow.
Deep Water Culture (DWC) + Recirculating direct water culture systems (also known as RDWC) + BubblePonics.
Drip Irrigation – Also known as trickle, micro or local irrigation. Uses small emitters to drip nutrients directly onto the roots or soil of your plants. Saves water and nutes, can be used with mediums and soil.
Ebb and Flow – Or Flood and Drain hydroponics is simply a method to flood your pots with a nutrient solution at regular intervals and then let it drain back into the reservoir.
Nutrient Film Technique (NFT) – Nutrients are pumped from the reservoir into a tray to form a thin film of nutrients constantly flowing with the roots of your marijuana plants dipped in them. There is no growing medium.
Wick system – One of the most basic systems to use, if you are just starting out and want to get going today, try this.
What you need to build a Water Culture system
Container to hold the nutrient solution (reservoir)
Aquarium air pump
Air line/hose
Air stones (or soaker hose) to create the small bubbles
Baskets, pots, or cups to hold the plants
Some type of growing media
How a hydroponic Water Culture system operates is easy. The plant is actually suspended in baskets right above the nutrient solution in the reservoir. Usually by styrofoam floating on top, or through holes cut in the lid covering the reservoir. The roots hang down from baskets the plants are in, and hang down directly into the nutrient solution where they are submerged. The roots remain submerged all the time 24/7. The roots don't suffocate because they get the air and oxygen they need from air bubbles rising through the nutrient solution, as well as from dissolved oxygen in the water itself.
The more air bubbles the better for water culture systems. The bubbles rising should make the water look like water boiling at a heavy rolling boil. The bubbles should be rising up through, and making direct contact with the roots as they rise to the top of the water to be most effective for the plants. There are actually two ways of providing aeration and dissolved oxygen to the nutrient solution.

Setting Up Deep Water Culture (DWC)

1 – The Reservoir
When growing marijuana in a deep water culture hydroponic system, the reservoir is where all the magic happens. Plants are suspended above the nutrient solution, where the entire root ball is submerged. Make sure your roots do not receive any light to prevent problems, the easiest way to go about this is by using thick, black plastic containers.
A cannabis plant needs a reservoir with a minimal volume of around 10-15 liters to complete its life cycle, ideally each plant gets its own reservoir for this. You can definitely grow multiple plants in one reservoir, but this does mean you can’t adjust nutrition as specifically. Use highly uniform strains or clones if you intend to grow more than one cannabis plant per reservoir.
The top of your reservoir should be a lid or anything that covers (most of) your reservoir and is able to hold a few kilos. The pot that will hold your cannabis plant is suspended in this cover, so make sure it’s built to last. It is especially important that your container can be supported on top of your reservoir, so make sure your lid can handle the weight of a fully flowering cannabis plant. A common construction flaw in DWC systems is that the “plant holder” can’t support a full size cannabis plant, causing it to fall through the top of the reservoir.
A large scale DWC hydroponic system will often use a large central reservoir that is connected to multiple smaller ones. This way you only have to mix one big barrel of hydroponic nutrients and hook it up to the system to feed all your plants. These recirculating deep water culture (RDWC) systems are definitely the way to go if you want to scale up your grow room, but aren’t required for smaller grows. If you’re just starting out with deep water culture, we’d recommend running a single reservoir with a single plant. With a few weeks of veg time you can fill out smaller tents quite easily with only one cannabis plant.

2 – Pots For A DWC Hydroponic System
The actual pot your cannabis plant is supposed to grow in is often left out in discussions about deep water culture. Ideally you’d use net pots that are specifically designed for use in a hydroponic system, but these are relatively unavailable throughout Europe. More experienced DWC growers know how to make decent containers out of just about anything, but this can be difficult for newer growers. Fortunately there are plenty of options if you’re a bit creative, we’ve seen anything from modified outdoor pots, to nets or baskets being used to hold up plants in DIY hydroponic systems.

3 – pH, Nutrients And Additives
A big drawback of DWC is that it also requires quite specific reservoir temperatures, ideally 17-20 °C. This is the reason this type of hydroponic system is hard to pull off well outdoors. For the average home grow however, this range is easily maintainable. During heat waves you can lower the temperature by adding a frozen bottle of or two or using an aquarium chiller. Cold reservoirs can be heated up using an aquarium heater. If you are attempting to grow in a location with very variable temperatures, it might be best to reconsider DWC entirely.

4 – Aeration For Your Cannabis Plant
The next step to setting up your own DWC hydroponic system is to figure out how you’re going to aerate your reservoir. The main advantage of DWC is that a cannabis plant will have unrestricted root growth, but this strongly depends on an abundance of oxygen in the reservoir. Without an air pump, DWC is simply not possible. DWC growers should always have a backup air pump, as a day without a pump will most likely kill your crop.
Choosing an air pump can be very confusing when first building a DWC hydroponic system as there is little and confusing information online. Pumps are usually rated by how much air they provide per unit of time, in this article we’ll use liters per hour so adjust accordingly if you’re using imperial units. We’ve seen recommendations going from 1 l/h per liter of reservoir, all the way up to 15 l/h per l. While lower is better for most parameters when growing marijuana, the opposite is true for aerating your reservoir.

5 – Strains For DWC
First and foremost, any strain will do well in a deep water culture hydroponic system as long as you give it the attention it needs. There are however big differences in how much attention different strains need. Because growing marijuana in a DWC hydroponic system goes hand in hand with floppy plants, shifts in pH and nutrient concentration and high humidity, it is a good idea to pick a strain that deals well with these issues.
Strains like our Jack F1 and Strawberry are amazing strains to grow, but they are more difficult to grow in DWC because they don’t like shifts in pH or nutrient concentration. More robust strains in terms of these shifts like Afghani Gold and Mega Power Plant are much less likely to be stalled by changes in the reservoir. Indica varieties are generally a little easier to grow in a hydroponic system, but that doesn’t mean sativa strains are incredibly complicated. Sativas will require more support and possibly more training due to their height, while indicas are bushier and usually need more defoliation.