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.
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.
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.
Deep Water Culture: Your Questions Answered!
by Sirius Fourside
Have you ever heard of hydroponics? Although the term is sometimes used to describe growing cannabis plants in any inert or soilless medium (for example coco coir), it more commonly is used to describe growing with plant roots directly in water and that is what most people think of when they hear the word ‘hydroponics’.
Cannabis Plants Growing With Roots Dangling in a Reservoir of Water
Here’s what’s inside! Since the cannabis roots get everything they need without having to “search” for it like they would in soil, you end up with faster vegetative growth rates. This growth is supported by huge masses of happy, healthy roots like this!
“Deep Water Culture” (commonly referred to as DWC) refers specifically to the type of hydroponics where plants grow with the roots stretching out into a tub of nothing but aerated nutrient-water.
This roots-in-oxygenated-water setup is what gives Deep Water Culture its remarkable vegetative growth speed!
Why is it called Deep Water Culture? “Deep Water” because the plants are growing in a deep pool of water instead of in some sort of growing medium, and “Culture” is a word that can also mean “Cultivation”.
As DWC has gained popularity for growing marijuana, we have been receiving lots of questions from hydro growers of all experience levels. Today, I’m going to answer some of the questions we see the most, as well as give you some helpful tips that will make your next DWC grow much easier and more rewarding!
Sirius: Also, I’ve mixed in some pics of my current DWC grow. It’s like a quick timeline of a cannabis plant’s life in a DWC setup.
What is DWC?
In short, DWC is growing your plant with its roots in aerated nutrient-water (the air part, provided by bubbles, is very important). Like this:
(Click the picture below to see an animated version [3Mb .gif])
Do plants really grow faster in DWC?
Yes, plants grow noticeably (and I mean noticeably) faster in DWC during the vegetative stage than they do in soil or coco coir.
Why is that? Vegetative plants growing in soil spread out a huge system of roots, then they use those roots to search for and uptake nutrients from the soil in which they live. Roots in soil also need to find pockets of oxygen to prevent the plant from “drowning”(lack of oxygen is what causes plants to droop from being overwatered).
When growing hydroponically, the roots don’t need to spread out, and they don’t have to ‘search’ for the nutrients since everything the plant needs is readily available in the most absorbable form possible. The dissolved oxygen in the water gives the roots almost unlimited oxygen and prevents the plant from getting “overwatered” or droopy even thought the roots are living in a reservoir of water. This decreased effort in having to ‘find’ nutrients and oxygen translates into increased vegetative growth and lots of foliage, especially if plenty of light is provided!
However, while buds may fatten up more in the flowering stage due to great environmental conditions at the roots, possibly increasing your yields, they won’t be ready to harvest any sooner after the flip to 12/12. The time to harvest is mostly dependent on strain, and DWC-grown plants take the same amount of time as any other plants to fully ripen and be ready for harvest. (Why Aren’t My Buds Ready for Harvest?)
Is DWC harder to do than soil?
Nope! Every method has its own quirks you have to watch out for, but with a little experience and a good setup, DWC can be just as easy as soil (if not easier) since it ends up taking so little time to manage.
Here’s a DWC setup in action!
Barneys Farm Liberty Haze Barneys Farm Critical Kush
Should I try DWC for my first grow?
Although DWC is a great (and my personal favorite) way to grow, I would definitely recommend trying coco coir as an introduction to growing cannabis. It is similar to a hydroponic grow in many ways, and will teach you most of the skills you will need to grow, but it a little bit more forgiving. I personally think coco is one of the best ways to get introduced to growing cannabis!
Once you‘ve completed a grow with coco, DWC will seem much easier. That being said, we’ve received many pictures from growers doing DWC amazingly well on their first grow just by following the tutorial!
I’ve already grown in soil. Do I need to be concerned with anything new when growing DWC?
When it comes to Deep Water Culture, the main difference if you’re used to a hand-watered growing medium is you need to pay attention to the reservoir. Peeking into the reservoir through an empty net pot hole lets you ensure the roots look happy and that the water level inside is properly maintained. It’s just like paying attention to your soil except that the conditions of water can change quite a bit faster. On the flip side, you have much greater control over the root environment in DWC than any other grow method!
Do I need an air pump?
Yes, it’s absolutely necessary! Your plant roots still need air, and without an air pump they will drown. Plant roots need oxygen, and the heavily oxygenated water in a DWC reservoir is a big part of why hydroponic plants grow so fast!
This is a time-lapse video of the seedlings from the last picture growing over 13 days.
Can I have the air pump turn off sometimes to save electricity?
I would strongly recommend against it; the air pumps should be running for 24 hours a day throughout your grow to give your plant roots lots of air and bubbles. Besides, it’s the grow lights that use the vast majority of the electricity.
If you’re worried about the noise, placing the pump on a solid, thick surface instead of directly on the floor will reduce the vibration quite a bit.
Is DWC safe to do?
Most definitely! Just make sure you don’t have electronics/plugs/outlets directly on the ground. This is a rule for all grows, however.
Is DWC as stealthy as other grow styles?
Slightly less so. A DWC setup requires an air pump to be running, and air pumps can make some noise depending on the model you get. Larger air pumps vibrate harder, which can become its own separate kind of noise!
Luckily, there are many models that pump out lots of air and run very quiet! EcoAir makes a pump that will run two large stones and you can barely tell it’s on. Placing the pump on something thick and solid (instead of directly on the floor) will reduce the noise even further!
Unrelated Tip: Exhaust fan too loud? Try hanging your exhaust fan from inside the tent instead of setting it on top; this will greatly reduce the amount of noise!
3 of the seedlings from before have been culled, and now only the strongest plant from each strain remains.
(Culled all but the two strongest plants; I prefer to have only one per container.)
How should I start seeds in DWC?
Rapid Rooters are – in my opinion – one of the best ways to start a seedling in DWC. They germinate successfully so often for us that that now if a seed doesn’t germinate, I assume the seed must have been a dud. The main thing to keep in mind with Rapid Rooters is to make sure they stay moist, but they should never look or feel wet. If it’s shiny, it’s too wet!
My second favorite germination method is the Paper Towel Method. It is simple but surprisingly effective at getting seedlings started fast.
Does my reservoir water need to be sterile?
No, but it has to be a good place for plant roots to live. Some people take the route of keeping their reservoir sterile – meaning it just has nutrients and water and no trace of anything alive.
Personally, I load my reservoir up with beneficial bacteria instead. This way, if bad neighbors like pythium (a fungus-like organism that causes root rot) move into my reservoir, they get out-competed by the good guys that already live there. There are a few good sources of beneficial bacteria for DWC, but I personally use Botanicare Hydroguard, which is a root supplement that is extremely effective at stopping and preventing root rot in a DWC environment.
With all the root space and light to themselves, two little plants soon turn into bulky shrubs!
Why does the pH of the nutrient-water go up right after I put it in the reservoir?
The pH of the water in a reservoir can change for many reasons, but when it happens right after you changed the reservoir, it may be because the water was sitting for a while and is now being agitated. Bubbles from the air pump move the water around, especially on the surface; this movement raises the pH of the water in addition to aerating it. This may be less noticeable if you shake your water up well before testing the pH and adding it to your reservoir.
In any case, after about an hour, you should notice the pH stays more stable (and that’s the pH level you should pay attention to).
There are a few other factors that change your pH over time. Your roots give off waste products that affect the pH, and as roots use up nutrients at different rates that can also alter the pH.
One thing you can do to help stabilize pH is keep your water level about 2 inches below the bottom of your net pots. A bigger reservoir has a more stable pH, so making sure your reservoir is always topped off will help improve pH stability. On the flip side, the air gap helps prevent the hydroton from affecting the pH, keeps stems from getting mushy, and also helps roots get more oxygen.
What is Top-Feeding?
Top-Feeding is something you add on to a DWC setup. It takes water from the reservoir and trickles it directly onto your seedling roots to encourage your seedlings to grow faster. This setup is what many people think of as ‘bubbleponics’.
Is Top-Feeding worth the trouble?
Top-feeding provides a very tangible benefit in the beginning of the cannabis plant’s life. Seedlings sprout and grow leaves faster in the beginning, but the benefits will definitely diminish after a few weeks. Once a plant is in ‘aggressive vegetative’ mode with a big root mass in the water, the effects of a top-feed will be practically nonexistent.
That being said, a grower can shave 1-2 weeks off of a grow with top-feeding, which makes the beginning stages a lot more exciting (and saves time / electricity)!
This is low-stress training. The stems are gently bent away from each other and held with twist-tie.
How many plants should I grow in a reservoir?
You can grow as many plants as you can fit, but 3+ will definitely be a crowded fit. As much as it pains me to say it, the most efficient configuration is to grow one plant per container. This gives the roots more room to spread out, but more importantly, it gives the leaves and buds room to spread out! It also gives you 5 extra ports to reach the reservoir without having to actually move your plants and possibly disturb the roots.
Do I really need to check the pH?
Checking the pH can be boring/tedious, but it’s also one of the most important factors in any grow, especially in DWC. Good pH management makes for pretty plants and bad pH makes for sickly plants. Think of pH adjustments like a supplement that makes your plants grow better and faster!
How often should I give new nutrient water to plants growing in DWC?
You can change your reservoir water for new nutrient-water every one or two weeks, but in the meantime they need to have the reservoir topped off with pH’d nutrient water at 1/4 strength. After a grow or two, you’ll notice that some strains (like BlackJack) will throw a fit if their water isn’t changed weekly, while others (like Wonder Woman) are hardier and can handle a wider array of conditions.
As a general rule of thumb, you should completely change your reservoir at least once every two weeks in the vegetative stage, and at least once a week in the flowering stage.
Cannabis plants respond well to low-stress training, like these ones from above. They filled up all of the empty spots we made!
How can I easily drain and replace the reservoir water?
A liquid transfer pump (also called a ‘water transfer pump’) is typically used to empty out aquariums or transfer gas between containers and a vehicle. If you’re growing cannabis in a DWC (Deep Water Culture) or similar setup, this type of tool can turn the often arduous job of changing your reservoir water into a quick 5 minute task!
The one I use is pictured here. This “battery-operated siphon liquid transfer pump” uses D batteries so you don’t have to worry about cords. This means that people who grow hydroponically don’t have to plan their grow area for the sake being able to empty/fill their reservoir more easily. It’s a good choice for hobbyist growers with 1 or 2 small reservoirs, though if you’ve got a big tank you’ll want something more powerful that can move a lot of water.
What are optimum nutrient levels for growing cannabis in DWC?
Always start with half of the recommended dosage on the schedule provided with your nutrient system. For example, I use General Hydroponics Flora Trio, so I just use the schedule on the back of the bottle divided by 2.
After that, dial it in! That means to watch your cannabis for signs of nutrient burn or deficiency. If it gets nutrient burn, reduce the nutrients from 50% to 25%. If it’s becoming lime green and the pH is between 5.5 – 6.5, increase the nutrients from 50% to 75%.
Buds are forming on the army of branches we made!
These plants are about to be defoliated one last time before harvest!
Can I mix up the nutrient water in advance?
If you’re using General Hydroponics Flora Trio, then the answer is yes! And that’s straight from the horse’s mouth! …the horse being General Hydroponics.
Although I haven’t confirmed this with every hydroponic nutrient company, colloquially, it seems that there is no problem at all with storing pH’d nutrient-water for up to a week as long as the nutrients don’t contain organic ingredients (like guano, kelp, bloodmeal, bonemeal, etc).
When in doubt, always contact your nutrient company to see how far ahead you can make your water! Most major nutrient companies have a contact form on their website and will get back to you in just a day or two. They know their products better than anyone!
What temperature should my reservoir water be?
Here’s the rule I use: If your grow room temperature is in a good range, then your reservoir temperature is also in a good range. You only really need to worry about your reservoir temperature if your grow room temperature is out of the acceptable range.
Many growers aim for their reservoir water to be between 60-68°F because cooler reservoir temps prevent some bad organisms from growing in the first place, and cool water can hold more dissolved oxygen in the 60-70°F range. However, cannabis can grow and thrive in much warmer reservoir temperatures as long as beneficial organisms are present to fight root rot. In fact, I personally have found that hydroponic plants tend to grow a little slower when their roots are cool, and grow fastest around 75°F (as long as you’re using a supplement with beneficial organisms to kill root rot).
Maintain the temps in your grow room and the reservoir is fine
I personally have found hydroponic plants tend to grow the fastest when the temperature is between 73-80°F, with 75°F being a good temperature to aim for. However, with warmer temps make sure you’re using a beneficial bacteria supplement to prevent root rot!
They’re just fattening up under the 600w HPS light! Due in about 4 weeks!Deep Water Culture (DWC) means growing your plant with the roots in a bubbling reservoir of nutrient water. This perfect root environment is what gives DWC-grown plants their remarkable growth speed! ]]>