If you’re looking for a hydroponic system that’s simple to set up and maintain, deep water culture (DWC) could be just what you need.
This method can easily be adapted to suit both home and commercial growers, with your efforts being rewarded with faster and more vigorous plant growth, as well as higher yields.
Let’s take a look at this tutorial:
- 1 What is Deep Water Culture?
- 2 Pros and Cons of Deep Water Culture
- 3 How to Set Up a Deep Water Culture System
- 4 Step By Step DWC Setup
- 5 3. Set Up the Plants
- 6 Cleaning a DWC System
- 7 Variations of Deep Water Culture:
- 8 Best Plants for a DWC System
- 9 Summary
Deep water culture involves keeping the roots of your plants constantly submerged in a deep container filled with an aerated nutrient solution.
DWC doesn’t require the use of a growing medium, although some growers still prefer to use one. Instead, the plants are placed into net pots that allow their roots to stretch downwards into the nutrient solution, soaking up all of the goodness that they need.
DWC ensures that your plants are always exposed to nutrients, water, and oxygen (thanks to an air pump) – the three components that lead to quick growth and healthy yields.
- Unlike some other hydroponic systems, DWC provides plants with plenty of oxygen, in addition to nutrients and water, which stimulates cell growth within each plant.
- DWC systems do not require the use of a growing medium or additional fertilizers.
- DWC hydroponics is easy to set up and maintain.
- Plants only take up the amount of water that they actually need, meaning that you don’t need to worry about overwatering.
- The system is easy to monitor, and due to how deep the water reservoir is, fluctuations in pH and nutrient levels are minimal compared to other hydroponic systems.
- Once your DWC system has been set up, maintenance costs are very low.
- Plants thrive in DWC hydroponics, and are usually ready for harvesting much faster than if they were grown in the ground.
- The lack of a growing medium means a reduced risk of pests and diseases.
- Smaller scale systems could still experience rapid fluctuations in pH and nutrient levels.
- The temperature of the nutrient solution is easily influenced by the ambient temperature of the environment around it, which can make it harder to control. Smaller systems often tend to run too hot.
- A constant electricity supply is needed in order to run the air pump. If this fails for whatever reason, the roots of your plants can quickly end up suffocated, leading to their death.
- DWC hydroponics isn’t great for starting seeds, since it will take some time for new roots to emerge through the bottom of its net pot to access nutrients and water.
There are a few main components involved in just about every DWC system:
- A water reservoir – it’s always best to go for the largest reservoir that you have the space for, since the bigger your reservoir, the less you will have to deal with pH and nutrient fluctuations. Large buckets work well as reservoirs – just make sure that the reservoir you pick has a well-fitting lid.
- Net pots – these pots have a large mesh at the bottom to allow plant roots to stretch through. Hydroponic net pots are widely available, but you can also make your own by creating large holes in plastic pots – just be sure to smooth down any sharp edges to prevent them from damaging growing roots.
- Growing medium – although this isn’t a must, using a growing medium does have its advantages, which are discussed in more detail further down.
- Air pump, air stones, and tubing – the size of your pump and the number of stones you need depends on how large your DWC setup is. However, make sure that your chosen pump can process double the volume of your reservoir per hour – eg. Go for at least a 200 liter per hour pump if your reservoir holds 100 liters.
- Nutrients – these will be discussed in more detail in the next section of this deep water culture guide.
The nutrients that you use in a DWC system depend on the type and age of the plants you’re growing. Some plants are much heavier feeders than others from the start, and just about every plant will require more nutrients as they grow, meaning that your nutrient solution will need to be adjusted throughout the growing process.
There are many pre-made nutrient mixes out there that are designed for hydroponics. Most of these will work very well in a DWC system.
However, if you would like even more control over the nutrients you’re feeding your plants with, you also have the option of making up your own nutrient mix. This tends to be especially beneficial to large scale growers, although it would be worth ensuring that you’ve got a good dwc nutrients guide to follow when doing this for the first time.
Since your plants will be constantly submerged in the nutrient solution, a growing medium isn’t a necessity when it comes to DWC hydroponics.
The exception is if you are growing seedlings – your growing medium will encourage the delivery of water and nutrients to young roots, since the roots themselves will be too small to reach deep into the reservoir.
However, a growing medium can help to ensure that your plants fit securely into their net pots. Some of the best options for DWC include:
Moisture retention isn’t a quality you need to be looking for in a growing medium for DWC. Instead, go for something relatively heavy, as this will help to hold your net pots in place.
Just like with any other hydroponic system, it’s important to keep a close eye on the pH level of your nutrient solution. This should usually sit between 5.5 and 6.5.
Again, this depends on the type and age of plants you’re growing – younger plants usually need a slightly higher pH, while plants that are flowering and fruiting will require a pH that’s a little lower.
While small fluctuations aren’t usually a problem, the issue lies when pH fluctuates significantly outside of the ideal range.
This can have a number of detrimental effects on your plants, such as:
- Blocking certain nutrients from being absorbed by your plants.
- Providing too many of certain nutrients to your plants, leading to toxic effects.
- Causing stress to your plants, which will severely affect their growth and could prove to be fatal.
There are plenty of reliable and inexpensive pH testing kits out there – these are a must if you plan on growing hydroponically.
As mentioned, it’s really important to monitor the temperature of the nutrient solution in your reservoir.
Ideally, this should sit somewhere between 17-20°C.
Any higher than this, and your plants will soon end up showing signs of stress. On the other hand, if the temperature drops below 16°C, your plants will think that winter is on its way, causing them to slow down growth.
A simple thermometer will be extremely helpful for keeping temperature in check.
It’s extremely simple to set up a DWC system.
1. Set Up the Reservoir
To start with, you’ll need to make some holes in your reservoir lid. The holes need to be large enough to accommodate your net pots, without being too large that the pots end up falling through as the plants grow and get heavier.
If you make a mistake and don’t have another lid, use a styrofoam sheet instead. Cut this to the size of your reservoir, and then make suitably-sized holes in it.
2. Set Up the Pump
It’s time to connect up your pump system – attach the air pump to the tubing, and attach the tubing to the air stones. Try to set things up so that the pump sits near to the reservoir, and then place your air stones into the reservoir.
3. Set Up the Plants
Get your plants ready by placing them into their net pots, ensuring that their roots are facing downwards.
If you’re using a growing medium, add this in around the roots of your plants to secure them in place.
4. Set Up the Nutrient Solution
Dilute your nutrient solution with the recommended amount of water (this will depend on the specific nutrients you’re using), and then add this into your reservoir.
At this stage, it’s really important to get the level of water right.
While you want the water level to be high enough to keep the roots of your plants submerged, you should still try to ensure that the top one and a half inches of roots are above the water. This is because the stems on each plant will grow longer over time, and if these end up in the water, they’ll rot – give yourself that extra bit of space as a margin of safety, since it won’t affect the growth of your plants.
As your plant roots grow, you will need to fill your reservoir a little less each time you replace the nutrient solution.
The exception to this would be if you are growing shallow-rooted plants. In this case, you’ll need your nutrients to be pretty much touching the bottom of your net pots to make sure that the roots have enough contact with the liquid.
5. Turn the System On
You’re now ready to turn your new DWC system on!
Don’t forget that you’ll need to keep a closer eye on it than usual during the first week or so. You will likely need to make some adjustments, whether this may be to the nutrient solution itself, the water level in the reservoir, or anything else.
Let’s see how to clean DWC system:
You will need to regularly replace the nutrient solution in your DWC reservoir. How often you do this depends on how hungry your plants are, but this should generally take place every one to two weeks.
Each time you remove the nutrient solution, you should also be giving the reservoir a quick clean. Once your plants are ready to be harvested and have been removed from the system, you should then give your system an even deeper clean, making sure that you remove any trace of organic matter.
The net pots that you use will also need to be cleaned in between plants.
Some growers choose to sterilize their reservoir each time they clean it, and will also sterilize the nutrient solution they use. This can help to reduce the risk of bacteria contaminating your system.
However, sterilization isn’t strictly necessary. While bad bacteria may be a small risk, beneficial bio-organisms will thrive in an un-sterilized system, which will be great for your plants.
If you like the idea of deep water culture but don’t want to, or have the right setup to, use an electric pump, then the Kratky method may be your answer.
The setup is exactly the same as a standard DWC system, but without including the air pump and air stones. Instead, the nutrient solution in the reservoir remains completely still and untouched throughout the growing process.
As the plants and their roots grow, the water level in the reservoir will start to drop. This creates more air space around the roots, giving them access to all of the oxygen that they need, while the bottom of the roots will still be able to reach the lowered water level.
By the time the nutrient solution reaches the bottom of the reservoir, the plants should be ready for harvesting. At this stage, they can simply be removed, so that the reservoir can be cleaned and replenished with new nutrients and plants.
The Kratky method requires a few extra calculations at the beginning. You will need to find a nutrient concentration that will give your plants everything they need until they are ready to be harvested, since you won’t be adjusting the nutrient levels at all.
Although the Kratky method may be extremely low-maintenance, allowing you to leave your plants unattended for long periods of time, it’s much harder to have full control over pH and nutrient levels, as well as temperature.
Algae growth can also be a problem with this method. However, you can get around that by making sure that your reservoir is covered in a light-proof material, or by placing clay pebbles over the top of your growing medium.
Bubbleponics is considered to be a hybrid deep water culture system, because it also makes use of elements from drip hydroponic systems.
DWC on its own isn’t a good method for starting seeds, since your new seedlings won’t be able to reach down into the reservoir to access nutrients until their roots are a certain length.
Bubbleponics gets around this by also feeding plants from above. The only extra equipment you would need for this is:
- Drip lines
- A water pump
Simply connect your water pump so that it sends the nutrient solution from the reservoir up to the drip lines, which you would place in amongst the plant roots in their net pots.
This sub-technique of DWC really speeds up the germination process, and also gives seedlings a strong start to life.
One DWC reservoir may provide enough space for plants grown on a smaller-scale, but those who want to grow on a larger scale would end up having to use multiple reservoirs. This can be extremely time-consuming, especially in terms of monitoring and adjusting ph and nutrient levels, which is where a recirculating deep water culture system comes in.
A recirculating system makes use of one large main tank that is connected to several reservoirs. The nutrient solution is placed into the large tank, where it then feeds each reservoir before being recirculated back to the original tank.
This method also means that only one air pump is needed for the entire system, although some growers do still place an air stone into each individual reservoir to ensure maximum aeration.
In addition to giving you more room to grow, this method also saves time – you only need to monitor the nutrient and pH levels of your main tank, rather than multiple reservoirs.
The main downside to recirculating deep water culture is the spread of pathogens. Any bacteria that happens to form in your system will quickly spread throughout all of your reservoirs, which could be highly destructive to all of your plants.
Some plants do well in all hydroponic systems, such as lettuces and herbs. This is because of how quickly they naturally grow, and the fact that they can be harvested while young and small.
However, a DWC system gives you even more options when it comes to plants that you can grow. Not only do the following absolutely thrive in DWC, but they show better growth and productivity compared to being grown in soil:
Easy to set up, inexpensive to maintain, and fantastic for plant growth – it’s easy to see why deep water culture is one of the most popular hydroponic growing methods out there.
Adaptable to both home and commercial growers, a DWC hydroponics system may take a little fine-tuning at the start, but you will soon find yourself growing healthier, happier, and more productive plants.