What is a Deep Water Culture (DWC) hydroponic system?
Types of DWC Systems
Since this tutorial’s main agenda is to run you through the steps to build a conventional deep water culture system, we’re not going to get into much details about each DWC system. That said, these systems are same in construction but with minor differences. Let’s have a look below.
The Kratky Method
The Kratky Method
The Recirculating Deep Water Culture System – RDWC
Since the conventional DWC system cannot be scaled up – there is need for a RDWC. Several buckets link to a central reservoir in recirculating deep water culture. The oxygenated nutrient solution passes through each plant before getting back to the tank. The system works in a similar way such as a cross between a deep water culture and a flood and drain system.
What makes it different is that nutrients remain intact in the growing area. In the RDWC system, each bucket can hold around 2 to 3 plants or more. Some can even lock six or more plants depending on the variety. The major challenge of having a large number of plants in a single bucket is that the plants will strife for the oxygen and nutrients. With this being said if your growing a smaller crop like lettuce having multiple pots is okay, if your growing larger plants like tomatoes we recommend only having one plant per bucket.
Bubbleponics is another type of DWC system that is precisely the same as the regular type but with only one difference – the addition of a water pump inside a reservoir. The purpose of the water pump is to supply the oxygenated water to the top of the net pots. In other words, this system is an improvised version of a conventional system for small plants whose roots can’t reach the water. Ideally this method is superb during the tender age of your plants. It aids the seedlings’ roots to grow faster.
What are the main components of a Deep Water Culture System?
Are you excited about building a dwc system already? Well, before you get there, here are three major components of the system:
Water is the most critical component of a DWC system. Plants require water to survive. Unlike growing crops in soil that require constant watering – DWC system eliminates that trend. Next time you hear about Deep Water Culture, think of water. Water is imperative.
Remember you’re growing your plants in the absence of soil. The soil has room for air circulation which is a different case with water. Well oxygenated water prevents the plants from drowning.
A plant needs both the micro and macronutrients to thrive. When using good soil for cultivation, micro and macronutrients are always readily available. For your plants to grow well, only oxygenated water is not enough. You need to supplement it with the necessary nutrients as well.
Which are the most suitable crops to grow in a DWC system?
You might be in for a big surprise if you don’t get this question right. The last thing you want to experience is a bunch of losses after investing both your time and funds in anything. To help you nail it right though, below are some of the crops to consider:
- Annual vegetables
- Strains (amnesia haze, purple queen, royal moby, skunk xl, blue cheese)
- Bok choy
There is much to know about each crop that probably you’ll have to dig quite deeper to understand how to go about it. In general, plants that do not produce flowers, and some herbs do well in the DWC system. Note that it is essential to do thorough market research before making a final decision. Once you’re through with your research you can factor in the following; crops hybridity, harvest potential, should be water-friendly, the weight of crops (should be lightweight) among other things.
Steps to set up a DWC system
Before you get started, you need to gather the following:
- Air pump (Aquarium ones work great and are very reliable)
- Airline tubing
- Growing media (gravel, perlite, clay pellets, marbles)
- Hydroponic nutrients
- pH control kit
- Net pots
- PPM Meter
- Drill and a drill bit
- Hole saw
Now let’s take a look at each of the above requirements in more detail to gain understanding.
The reservoir is the backbone of the whole system. It should be a dark container, preferably black. The reason for having a black bucket is to prevent light from getting inside. The crops’ roots should not be exposed to light. If they do, algae will be a problem. In a DWC setup, plants suspend above the reservoir containing the nutrient solution. The roots will grow down to the solution.
Due to the different types of DWC systems, as we discussed above, not all reservoirs will look alike. Some will have separate repositories while others will have one large shared pool. The best way to go is having each crop with its own reservoir. If you decide to use one giant tank, then be ready to cope up with the emerging challenges. Some plants can grow at different rates and maintaining the required nutrients levels will be tricky.
The recirculating DWC uses one large tank containing the nutrient solution that is connected to several smaller reservoirs. A regular DWC system uses a simple pool with a single crop.
The reservoir / water need oxygen. This process is only made possible through three things, an air pump, an air stone, and an air tubing. The air pump supplies the nutrients solution with oxygen. The air goes from the pump and passes through the air tubing and then towards the airstone which then delivers oxygen to the reservoir/water.
Choosing the best type of air pump can be a challenge. We recommend going for one that delivers twice the liters per hour of the volume of your reservoir. Make sure you test whether your air pump works fine before you set up the whole system.
Net pots and the Growing Media
Net pots design is specifically for growing hydroponics. Unfortunately, getting these net pots has always been a challenge in particular locations within Australia. Although you can make your own, it is recommended to purchase them since they do not cost much. If your struggling to find some net pots you can view a massive collection by clicking here. Apart from holding your crops, these mesh pots are what houses your growing media. You need to germinate your seeds before planting them in the net pots. During the first days after you transplant your seedlings, you’ll need to use the bubbleponic technique to help your crops get the nutrient solution (otherwise you can also hand water for the first week or two until the roots have reached the top of the water level). For the growing media, do a little research about the type of plants you’d like to grow and what medium other people are using. Usually clay pebbles are the most common choice among growers.
pH Control Kit and the PPM Meter
When it comes to hydroponics, pH control is significant. You want to ensure that the nutrient solution is neither too high nor too low. If you don’t monitor your pH well, you’ll likely have sick plants which will result to slow growth and low yields. The purpose of a pH control kit is to help you test your nutrients solution in a very convenient way.
For instance, to determine the nutrient pH, fill your test tube halfway with the nutrient solution. Add three drops of pH test indicator and mix the solution. Observe the following:
Yellow to yellowish-green indicates the required pH range for plant growth,
Orange or Red indicates the pH is too low, and,
Blue or Blue-Green indicates the pH is too high.
Always ensure that the pH of your nutrient solution is within the required range. The ideal range is 5.5-6.5.
The Parts Per Million (PPM) Meter is to help you measure the concentration of elements in the nutrient solution.
You can also buy meters and testers that you can stick directly into the nutrient solution. These do cost a bit more than the test kits but they do last longer and are a much quicker and more efficient way of measuring your nutrient levels.
The best nutrients to use with DWC system are the mineral-based nutrients. You should strive to look for nutrients with excellent pH stability in your solution. It is not always a walk in the park to identify which nutrients are suitable for your crops. Choose to go for a pack that contains all of the essential nutrients for crops growth. These nutrients include nitrogen, phosphorus, potassium, magnesium, calcium, sulfur, iron, manganese, zinc, copper, boron, and molybdenum.
These tools are essential during the construction process. They include, a hole saw, a drill and a drill bit, and a jigsaw.
Note that you’ll need a hole saw with same measurements as your net pots or slightly smaller. It will save you time and enhance your accuracy - especially if your making a few buckets. For instance, if you buy 80mm net pots, then you’ll have to buy an 70-75mm hole saw. You can also buy adjustable hole saws which we at the Hippie House use. This allows you to adjust the holesaw from anywhere between 50mm to 6 inches.
Now that you understand the purpose of all the equipment, it’s time to build a single bucket DWC system!
In this walk through, we’re building a system for one net pot. But the steps can be followed to create a dwc system with more net pots. Below are three simple steps.
Decide on the size of your container. An ideal one could be a 20 litre bucket with a lid. Once your bucket is ready, cut/drill holes into the lid for the net pots and the airline.
If you decide to use a jigsaw or holesaw, then measure/mark on your lid according to the diameter of your net pot. Make sure the hole to hold the net pot is not too big as otherwise the pot will drop inside the reservoir.
Use a drill bit (according to the size of your air tube) to drill a hole for the airline tubing. Since a single air stone is enough, we only need one hole. Now place your net pot and the air tube in their respective holes to make sure they fit well.
Now connect the airline to the air stone. Place the air stone at the bottom of your reservoir (bucket) then pass the tube through its hole in the lid. Next, plug the airline in the air pump. Fill the bucket with clean water until the bottom of the net pot is 3/4 –inch covered. Test the air pump and ensure it works fine.
Your DWC system is now ready. What next? Follow the procedure below to set up your crops.
How to set-up the crops after building your DWC system
- Start by germinating your seeds using a Rockwool cube (starter cubes) or jiffy pellets. This is essential as you cannot plant the seeds directly in the net pot.
- Fill your net pot with growing media of your choice. Note that the bottom of the growing media in the net pot should be moist but not soaked. The top inch should be completely dry.
- Next, mix your nutrient solution in the water in your reservoir. Follow the manufactures instructions carefully. Test the pH. Make any adjustments if needed.
- Place your net pot into the dwc bucket. Up next is to transplant your seedlings.
- After you successfully transplant your seedling, its time to make sure the roots grow. Since the seedling’s roots need to access the nutrient solution, you’ll have to water them at least for a week. Otherwise you can also use the bubbleponic technique.
- Keep an eye on your crop as it grows - especially at the start to ensure everything is working smoothly.
Now that we’ve built up a regular DWC system and set-up our plant, you’ll notice that attending to many buckets one at a time is time-consuming. This proper DWC system cannot scale big. If you want to grow more than one plant in DWC you'll want to set up a RDWC as mentioned above. We'll now discuss how to link several DWC buckets together.
How to link several DWC Buckets?
It is possible to link several buckets together. You can connect two, four, six, eight, or more. The choice is yours. Let’s see how to go about it.
- Growing buckets (20 Litre buckets)
- A control tank – the same height as the grown buckets
- A large water pump (submersible water pump)
- A large air pump
- Supply reservoir (optional)
- A bulkhead fitting or grommet
- Manifold and tubing (black)
- Vinyl tubing (if you use round gallons)
- Several valves
- Solvent weld fittings
- Tees, pipework, and elbows (optional)
- Water level indicator
- A hole saw
- Hose clamps
- Drill and drill bits
- Several net pots
Overview of a 4 bucket system
Sometimes it's easier to view a system to understand - in the image you'll a see a 4 bucket dwc system with the additional reservoir bucket.
What to do:
- Start by marking/measure your pipes and where you’d like to fit them in the buckets. You want to ensure that the hole for your tank connector and bucket is very close to the bottom. But again, ensure that there’s room to screw on the nut / fit the grommet.
- Once you’re done doing this, it’s time to start assembling. Attach the return pipes to your buckets. Use the bulkhead and note that the rubber washer goes to the outside. Now keep measuring, cutting, trimming, and join together the return pipes to the reservoir.
- Now drill single holes on the lids for your airline. Attach them to the air stone and place them at the bottom of the buckets. Connect the airline to the air pump.
- You now have your system put all together.
- If your using a grow tent, the suitable place to put your reservoir or control tank is outside the tent. You put it out to ensure that the temperatures are maintained and not to waste light space.
- Also sit your air pump outside, at a well ventilated, cold, and dry place. You want to ensure that the air drawn in is pure.
- Fill your control tank with the nutrient solution and turn on your pumps. Use your water level indicator to monitor the water level.
- If you decide to use a separate supply reservoir, then erect it a high level so that the nutrient solution will flow to the control tank via gravity.
The Bottom line With DWC Systems
Deep Water Culture systems pros surpass its cons. The system is not high maintenance and very easy to assemble. Crops grow very fast, and the yields are superb due to uniform uptake of nutrients. It is an excellent hydroponic system for beginners to start with and build their skills and understanding.
The best tip we have if your starting a DWC system is invest in a back up air / water pump. We have seen this over and over again - people spend 6 months growing their crop then the air pump breaks. If you can't source one locally and fast, within a matter of hours the plants will drown and you've wasted a lot time and money!