Deep Water Culture (DWC) is a special type of hydroponics where you grow plants with their roots immersed in an aerated nutrient solution. Find out how more and more cannabis growers are using DWC to achieve faster growth and larger yields.
While some cannabis cultivators simply grow plants in soil, others look into more elaborate growing techniques, such as hydroponics. Deep Water Culture (DWC) is one method of growing cannabis hydroponically that can have many advantages. Find out what makes a DWC grow so rewarding, and how you can set up one of your very own!
WHAT IS DWC?
Deep Water Culture (DWC) is a style of hydroponic growing that does not use a medium. In a DWC setup, the plants are suspended in special pots or nets, with their roots stretching down, immersed into a pool of aerated, nutrient-rich water. Growing cannabis in a DWC setup can have many benefits as compared to some other growing methods.
WHAT ARE THE ADVANTAGES OF DEEP WATER CULTURE?
FAST VEGETATIVE GROWTH AND BIGGER YIELDS
Plants grown in DWC setups have easier access to oxygen and nutrients, which means they spend less energy searching for nutrients and developing roots. As a result, plants will reward you with fast vegetative growth and excellent yields. In a good DWC setup with the right nutrients and strain, cannabis can grow as much as 10cm in a single day!
Know that the speed of growth in a DWC doesn’t affect when your plants will be ready to harvest. The fast veg growth will result in bigger plants with fatter buds, but they will still require a normal flowering time.
REDUCED RISK OF PESTS
Since a DWC setup doesn’t use any growing medium, there is little risk of bugs and other cannabis pests latching on.
PLANTS CAN GROW LARGER
The lack of growing medium in a DWC allows your plants to take advantage of all the available space and nutrients to grow as large as possible.
Once a DWC system is set up and running, it requires very little everyday maintenance. You can even leave it alone for over 24 hours.
WATERING IS LESS DIFFICULT
A DWC system is fully automated, which means you don’t need to worry about under or overwatering your plants. Once set up properly, your DWC will always supply the right amount of nutrients and oxygen to your plants.
IS DWC SUITABLE FOR NEW GROWERS?
There is still a myth going around that DWC is “difficult”, but nothing could be further from the truth. It is really no more difficult than any other growing method where each has its own quirks and inconveniences. In fact, a DWC system can ultimately be one of the easiest methods to grow cannabis since it requires very little time and maintenance.
However, if one is still new to growing cannabis, it can be recommended to first grow hydroponically using a substrate like coco. This is because coco can be more forgiving, which allows the grower more room for error. That being said, there are plenty of cultivators who started out with a DWC setup and found success right away.
HOW TO SET UP A DWC GROW
For growing cannabis in a DWC, you will need these things:
- Water/nutrient reservoir (shared or individually for each plant)
- DWC net pots to hold your plants
- Hydroponic nutrients
- Air pump (and air stones) for the aeration of your nutrient water
Now, let’s take a look at each of these DWC components in more detail:
1. THE RESERVOIR
One difference of using a DWC system as compared to growing in a medium such as soil is the reservoir. In this setup, plants themselves will be suspended above the reservoir containing the feeding solution, while the roots will stretch down where they will be fully immersed in the nutrient-rich “deep water”. Since the roots should not receive any light (to prevent issues such as the growth of algae), the reservoir is normally a light-proof container.
There are different types of DWC systems: Some setups may have one large shared reservoir for a number of plants. Other setups may consist of several smaller DWC reservoirs for each plant. Separate reservoirs like this have the advantage of allowing more control over each individual plant. Otherwise, if you grow multiple plants that share one reservoir, it can become tricky when you grow different strains or when your plants flower at different rates. Therefore, you should grow only the same type of strain if you have a system that uses one large reservoir.
Recirculating DWC systems make use of one large tank that is connected to a number of individual smaller reservoirs for each plant. The feeding solution is fed from the large tank to each of the plants, and is recirculated back into the tank. Some systems may just have one air pump and an air stone in the large tank, while others may have an air stone in each container for each plant. Air stones create bubbles to ensure proper gas exchange.
Simpler systems for single plants may consist of one reservoir, a small pump, and an air stone for one plant. Due to the dramatic growth of a plant in a DWC, a small, single-plant DWC system could be sufficient to fill-out a small tent in just a few weeks.
2. DWC NET POTS
In well-sorted grow stores that carry products for hydroponics, you can get so-called “net pots”, which are suitable for DWC systems. As compared to normal planting pots, these pots have a wide mesh so that the roots can easily reach the water below.
Alternatively, you can make your own DWC net pots out of almost anything by creating a number of large holes in containers or plastic flower pots. The difficulty here, however, is that cutting or drilling might result in sharp edges that could damage the sensitive roots. One good way to go about this is to use a soldering iron where you burn holes in the sides, rather than cutting or drilling them. (Do this outdoors since the fumes from burning plastic can be hazardous). You can also use baskets or nets for your DWC system.
Fill your net pots with an inert growing medium with low-water retention such as perlite, clay pellets (hydroton), or lava rocks. For germination, it’s best when to start out your seeds in Rockwool and transfer them over to your DWC after a couple of days.
Note: When your seeds have just germinated and are now sitting in pots in your DWC, the roots will obviously not be long enough yet to reach into your reservoir. Until this happens, you will have to top-water your plants. Some more elaborate DWC setups do top-feeding/top-dripping where water from the reservoir also trickles directly over the seedling’s roots. However, top-feeding will provide a benefit for about two weeks when your plants have just sprouted, which is why many growers forgo this addition in their DWC setup.
3. HYDROPONIC NUTRIENTS AND ADDITIVES FOR YOUR DWC
Aside from using quality hydroponic nutrients in the recommended dosage for your particular reservoir, one of the most important things for hydroponics is pH value. Most of the time, if something goes wrong with a DWC grow, it is likely because of a pH imbalance. For your DWC, the ideal pH is around 5.8. Make sure not to stray out of a pH range between 5.5 and 6.5.
One advantage of DWC is that it can require less nutrients than other growing methods. However, you should be regularly monitoring the pH of your feeding solution. To correct any pH issues, you can get ready-made products such as a “pH Up” and pH Down” in any good hydroponics store. Most of the time, you will only need a few drops of these pH correctors.
- How Often To Refresh The Reservoir?
There are no rules set in stone for how often you should renew the reservoir in your DWC. Some growers drain and exchange their water every one or two weeks, although some go longer than that. Whether and when to top-off or exchange your reservoir contents will depend on how much nutrients your plants use.
For this reason, one of the most important tools in your DWC will be a good ppm/EC meter. With this meter, you can keep track of any fluctuations. With some experience, and by monitoring your plants’ nutrient intake, it might be possible to get through an entire grow without having to exchange your reservoir until your final flush. You may just be able to top-off your tank with nutrients to maintain your desired ppm value.
4. AERATION FOR YOUR DWC SYSTEM USING AN AIR PUMP
Your cannabis plants need oxygen to grow, which makes the air pump in your DWC a most critical component. In fact, many growers keep a backup emergency air pump should one stop working. Understanding that just one day without a working pump could likely kill your crops, having a backup pump will be smart and provide you with peace of mind.
- Choosing An Air Pump For Your DWC
When looking around online, you will find lots of different air pumps offered that are not very expensive. You can get quite powerful pumps for less than €30 today. A problem, however, can be choosing the right one for your DWC system. Air pumps mainly differ in how much air they can pump per hour.
As a general rule, you should get an air pump that can supply at least double the litres per hour of the volume of your reservoir. For example, if you have a 100l tank, get a pump that can supply 200l/hour. Know that an air pump costing you no more than a few euros will likely not last a lifetime, so get the backup pump as well. And while you’re at it, also get some more air stones. It’s always better to be safe than sorry!
- Air Pumps And Noise
Modern air pumps can be quiet, yet the overall noise from a DWC system from vibrating parts can still be a concern, especially if you want to keep things stealthy and under the radar. Your air pump will likely be the noisiest part in your setup, but there are things you can do to make it even quieter. You could hang the pump instead of putting it on the floor, which can help minimise unwanted vibrations and noises. When you glue on any loose and wiggling parts from your DWC system, such as tubes or whatever else might rattle and shake, this can also make a big difference when it comes to noise levels. For large pumps, you can put these into a noise-isolating chamber as long as you make sure that the pump can still get air to function.
THE BEST STRAINS FOR DWC
You can grow pretty much any strain in a DWC if you keep a close eye on everything. On the other hand, some strains are less susceptible to fluctuations that can happen in a DWC system, making them an overall better choice for hydroponics.
When selecting strains to choose for your DWC grow, you may want to opt for plants that have tried and tested success in hydroponic grows.
Here is a list of strains by Royal Queen Seeds that can tolerate nutrient/pH fluctuations well:
Royal Moby by Royal Queen Seeds is a potent, sativa-dominant hybrid that can handle large amounts of nutrients without being overfed, which makes her a great choice for DWC. Get ready for a powerful high thanks to her 21% THC!
Amnesia Haze by Royal Queen Seeds is made from old-school Haze genetics, and is considered by many to be one of the best Haze varieties. The super-potent sativa (70%) delivers a truly psychedelic head high, and is very well-suited for hydroponics, including DWC.
The legendary strain from the UK blended with the fruity aroma of Blueberry: Royal Queen Seeds’ Blue Cheese doesn’t just taste amazing—the strain takes on a great shape when you grow her in a SOG or DWC.
An absolute classic, Skunk XL is Royal Queen Seeds’ modern version of the legendary Skunk #1. This 50% sativa/indica hybrid has a well-balanced effect that mixes an uplifting head high with a relaxing body stone. She does well in many conditions including hydro, and takes a particular liking to DWC.
Purple Queen by Royal Queen Seeds is an indica-dominant cultivar that blends the qualities of purple phenotypes of Kush mountain strains. This gorgeous lady loves to show off beautiful colours and rewards you with a deeply relaxing smoke. She has a high tolerance to fertilisers, which makes her very suitable to grow in DWC.
Growing cannabis in Deep Water Culture doesn’t need to be difficult. It may require some fine-tuning at first to get everything right, but so does any other growing method. Once you have your DWC set up and running with everything in check, it will make growing great cannabis easier and quicker than before.
Good luck with your first DWC grow!