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Get Huge Yields Using Deep Water Culture (DWC)

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.

LOW-MAINTENANCE

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.

Too many fertiliser salts can obstruct nutrient uptake and cause wilting. Use the DiST 4 Pocket Conductivity Tester for accurate readings.

Too many fertiliser salts can obstruct nutrient uptake and cause wilting. Use the DiST 4 Pocket Conductivity Tester for accurate readings.

  • 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:

1. ROYAL MOBY

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!

2. AMNESIA HAZE

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.

3. BLUE CHEESE

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.

4. SKUNK XL

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.

5. PURPLE QUEEN

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.

CONCLUSION

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.

Deep Water Culture is a great method of growing cannabis hydroponically. Learn all about DWC and be rewarded with fast growth and extraordinary yields.

Setting Up Deep Water Culture (DWC) In 5 Easy Steps

If you’re into growing marijuana, you’re probably aware that using a hydroponic system has a lot of benefits over growing in soil. What stops most growers from getting familiar with hydroponic cannabis cultivation is the idea that this is much more difficult than growing in soil. We already discussed how this isn’t necessarily true in our “7 Easy Steps To Start Growing Cannabis In A Hydroponic Setup” guide, but didn’t talk about Deep Water Culture (DWC) at all! DWC is often regarded as “the most difficult” way of growing marijuana, in this article we’ll try to convince you it’s actually quite easy.

Of course, the best part is how cool the roots look without any medium!

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.

These two plants are growing in the same reservoir, but the one in the bottom looks like it’s a week ahead! Different phenos can make feeding a lot more difficult.

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.

If you want to use deep water culture on a larger scale though, a recirculating system is the way to go!
Big plants like this can easily put 5 kilos of pressure on your DWC bucket lid.

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.

Net pots are specifically made for growing in a hydroponic system, but these aren’t available everywhere unfortunately.

Problems with these DIY pots usually involve the holes in the bottom being too small or too sharp, which can really damage a plant’s root system. Our favourite DIY solution is to burn as much holes as possible into a 200ml container using a soldering iron. The shape of these pots also makes it very easy for them to be held in place.

A soldering iron makes clean holes with rounded edges, but make sure you do this in a well-ventilated area.

You’ll usually fill this container with hydroton clay pellets, lava rocks, perlite or another inert medium with low water retention. We prefer hydroton clay pellets for their ease of use and availability. You can technically germinate directly in these pots, but it’s much more reliable to germinate in a starter plug. Any starter plug is fine really, but we prefer rockwool cubes for practical reasons.

In our general DWC workflow we germinate a seed in a rockwool cube and transplant it into the container a day or two after germination. You’ll still have to top water your cannabis plant during the very early stages unless you incorporate a drip system. As soon as the roots hit the water however, your plant will start to explode.

A top drip system like this will make the first week or two much easier, but won’t do much after that. We’ll leave it up to you whether this is worth the effort!

You can also start at a higher water level for the first week or two, keeping the bottom of the container just barely under the water line. The water level should be much lower for the remainder of the grow however, as a root rot is always a threat. Containers should be a good couple of centimeters above the water line for majority of the grow cycle.

In this image you see a cannabis plant in a DWC system. The two diagrams on the left side include a water pump because the plant requires top watering as long as its roots can’t reach the nutrient solution yet. Once the roots start touching the water this wont really be necessary anymore and the plant will start growing explosively.

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.

If you only have heat issues for a few weeks per year, the “hillbilly chiller” method of throwing in a bottle of ice is usually the most practical and cost-effective.

As we already discussed in our “7 Easy Steps To Start Growing Cannabis In A Hydroponic System” article, the average hydroponic system will be quite finicky when it comes to pH. The pH value of your nutrient solution is the most likely culprit when anything goes wrong in a DWC grow. Ideally you’d keep your pH at 5,8, but anywhere between 5,2 and 6,2 should be fine. A DWC hydroponic system might not require new nutrients as often as other systems, but you should definitely measure and adjust the pH regularly. Using diluted pH-down can make adjustments in a smaller dwc grow system much more practical. Nutrient lines that include a buffering component like Advanced Nutrients’ pH Perfect and Canna Aqua are especially practical in DWC grows, but not essential. You’ll have to check pH regularly either way, but a more stable pH is easier to maintain and much better for your plants.

Growing marijuana in a DWC hydroponic system means these two meters will become your best friends quickly!

Most DWC growers will recommend refreshing the entire reservoir every week or two, but you can get away with less. If you keep an eye on your ppm/EC values, you can usually avoid draining your reservoir for the majority of a grow. As the reservoir is drained, you can tell how much nutrients a cannabis plant uses by tracking differences in ppm or EC. If this information is used well you can usually completely avoid emptying reservoirs until the final flush.

Ideally your plants would use nutrients at the same rate as the water they’re dissolved in, but differences will generally arise at some point. In many cases a cannabis plant will use much more water than nutrients. If values remain the same or drop as the water level goes down, you can safely add another dose of nutrients. If ppm/EC values rise as the water level drops, you should only top off with pH adjusted water.

The “clean” way to run DWC is by refreshing the entire reservoir at every feeding. The “quick and dirty” way to do it is by refilling your reservoir indefinitely. This chart shows how you should top off your reservoir to maintain a ppm value of 1000.

If you choose to maintain reservoirs this way we do recommend always running enzymes, as this will help prevent a buildup of waste and unused nutrients.

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.

Air pumps are cheap and effective, this little 35 euro pump produces 3600 litres per hour.

We recommend getting a pump with at least double the liters per hour as the volume of your reservoir. For a 25 liter tank, we’d get at least 50 liters per hour of air flow. This doesn’t have to break the bank at all as cheap, 10 euro DIY store aquarium pumps often already produce around 100 liters per hour. Cheap pumps are fine, but make it extra important to have a backup pump close by. A single air stone per plant is technically enough, but we recommend using a second airstone just to be sure.

Components in air pumps are often installed without being 100% secured, which means they vibrate and make a lot of noise! You can fix this by gluing any vibrating parts to the body of your pump. Make sure you work safely though!

The capacity of your pump might not always be the main issue. A common mistake when setting up a DWC hydroponic system is not plugging in the pump until the very last moment, only to find out it makes more noise than your car. A stealthy DWC grow is usually limited by the sound of the air pump, so make sure you check this before buying anything. After buying a pump you can often reduce the noise by hanging it up and gluing any vibrating parts stuck. If you are set on using a larger pump you can also build a noise reduction chamber around it, similar to the way this is often done with exhaust fans.

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.

Our Gold Bar Kush isn’t the easiest strain in the world, but performs extremely well in DWC!

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.

Most strains are developed for either outdoor soil systems or indoor hydroponics, so make sure you buy a cannabis strain that was developed with hydroponics in mind. Many of our strains were selected for their viability in hydroponic systems, so a large part of the Spliff Seeds catalogue is very suitable for DWC. Strains like our AK and White Widow deal well with high humidity, changes in nutrient concentration and pH shifts, making them ideal strains for growing marijuana in a DWC hydroponic system.

Final Thoughts

By breaking down the workflow of growing in deep water culture, we hope the idea behind this type of system has become a little less complicated. DWC requires a few parameters to be well organized, making it an excellent way to learn how to work with hydroponics. Once you have all these parameters dialed in though, growing is suddenly very easy and you’ll understand why people like growing in hydroponics so much. Give it a shot, we wish you the best of luck growing in this amazing hydroponic system!

If you’re into growing marijuana, you’re probably aware that using a hydroponic system has a lot of benefits over growing in soil. What stops most growers