Of all hydroponics systems, Deep Water Culture (DWC) – also commonly known as bubbler systems or bubbler buckets is comparatively cheap, reassuringly simple and hugely effective.
Nowadays there are loads of different ways to grow your plants hydroponically – NFT, Flood & Drain, Drippers, Aeroponics and so on! When used correctly, the growth rates and yields that this technique can achieve are phenomenal. And that’s not all! DWC is very cheap in comparison to other options, offering simple, DIY setup beginners and more established growers both appreciate.
so no wonder more and more people continue to explore the option of Deep Water Culture (DWC) as a growing method.
How exactly does DWC work?
1. Basic Deep Water Culture
Deep Water Culture represents exactly what its name implies. Roots are literally submerged in “deep water” nutrient solution throughout your grow whilst an Air Infusion Pump generates a rich supply of bubbles around the root zone. Without vigorous aeration, submerged roots would rot and die – but when the bubbles are constantly present some surprising results often transpire!
The net pot is suspended over a nutrient-rich solution that is aerated with an air pump attached to an air stone. As the plant grows, the roots will travel through the Hydroton and net basket and grow directly into the nutrient solution thus providing the plant with a perfect ratio of nutrients and air to promote vigorous root and plant development.
2. The Kratky Method
Deep Water Culture without any pump is known as the Kratky Method. This is the most basic form of hydroponics with minimal equipment and without any use of electricity. In this passive system, you leave an air gap between the water (nutrient solution) surface and plants’ roots. Some parts of the roots are exposed to the air for oxygen while the other parts are submerged in the waters to get nutrients.
This method works best with fast-growing leafy green plants like lettuce, spinach, and herbs. It’s not efficient for larger fruits bearing like tomatoes, peppers, and cucumbers. Growing larger plants will not only need a larger container but more regular checking to ensure the water and nutrient level for water and oxygen access to the roots.
Bubbleponics takes the same idea of basic DWC (Deep Water Culture) with extra top-feeding/top-dripping where water from the reservoir is pumped directly over the seedling’s roots. The top-feed enhancing growth significantly in the first 2 weeks when your plants have just sprouted. Many cannabis growers use this technique as the roots get easy access to water from the beginning this way.
As soon as the roots hit the solution, Bubbleponics growers disconnect the top feed but keep the water pump on 24/7 in the reservoir to make a recirculating DWC system which is our next type of DWC.
It worked out so well that now I have water pumps in the bottom of all my reservoirs for recirculation
4. Recirculating DWC System
If you plan for a larger DWC system to grow multiple plants in multiple containers, you must set up a recirculating system. As, checking each isolated DWC system individually can be very tedious and time-consuming for pH, nutrient levels, and topped up with lost water.
Moving the water around not only increases the reservoir volume size but also helps to collectively maintain nutrient density, water pH and oxygenation. The constant water circulation diffuses any mineral concentrations or buildup of acidity throughout the entire water supply in numerous smaller systems.
Pros of DWC
Plants exposed to greater levels of oxygen in and around their roots will subsequently enjoy unparalleled root development and prolific overall plant growth. This is because aerating the root zone radically improves water absorption, nutrient uptake and cell growth/activity within your plants. It also helps stop water from becoming stagnant which can otherwise lead to root health problems such as pythium.
Cons of DWC
As with every growing system, there are a few drawbacks!
- Your plants are literally growing in the reservoir meaning pH and cF of this relatively small amount of nutrients will vary greatly – even over the shortest periods of time.
- Because the system is effectively just a bucket, the only way you can top up/pH adjust/test nutrients etc is to lift the whole plant up and out of the bucket. This sometimes proves difficult and hazardous to your plants when they are at full size.
- As the reservoir is very small, it requires regular attention to ensure that you always have enough nutrient solution available to your plants.
- If the air pump fails, your plants will die. Given that roots are completely submerged in DWC, when the aeration is not constant they inevitably deteriorate very quickly – ultimately threatening the life of your plants.
Parts of DWC System
A DWC system consists of a bucket (reservoir) with a lid, net pots, an Air Infusion Pump, Air Line, and an Air Stone. You may also need a water pump, timer, pH testing kit, and foliar feeding.
1. Bucket (Reservoir)
2. Air stone & Pump
However, you also need a water pump in a Bubbleponics setup to bring water from the reservoir up to the plant’s roots and in a recirculating system to pump the water through several reservoirs. Both the airstone and the water pump run 24 hours a day.
Are you stuck on what the sized water pump your system needs? Check this ultimate guide about the best hydroponics water pump and timer setup here
3. Net Pot
4. Growing medium
Read more about a list of 17 growing media used in hydroponics here.
Important factors in growing with DWC
1. Reserviour size and DWC yield
The volume of your grow tank is 4m x 20m x 0.25m = 20m³ = 20,000 litres. To turn this over in 2 hours requires a pumping rate of 10,000 L/hr.
In turn, your control tank of 1000L would be turned over 10 times per hour, with a calculated residence time of 6 minutes.
Presuming that you are mainly growing leafy greens, depending on what you grow, your plant density is probably about 20 plants/m². Hence, the total plants in your grow tank would be about 4 x 20 x 20 = 1600 plants. That is, for a total solution volume of 20,000 + 1000 = 21,000L, your volume per plant is 21,000/1600 = over 13 L/plant.
For comparison, for NFT (nutrient film technique) channel systems, the typical suggested minimum is only 0.25 L/plant, although preferably higher. Therefore, the analysis of your recirculating nutrient solution will be very much slower to change.
pH control could be more difficult, so I suggest that if your pH drifts, you change the ammonium content of your formulation to offset any drift. Alternatively, find out how much acid you need to add to stabilize pH and add this to your fertilizer mix, rather than adding separately. You should occasionally use the pH test kit to check and adjust the pH level of your system whether is too low or too high.
3. Dissolved Oxygen
You should not shut off the air pumps in your system unless you have a huge water volume per plant. Shutting off the recirculation pumps has the risk of you getting significant oxygen depletion overnight. Nevertheless, I would recommend that you do some pumping overnight in case there is stratification within your growing tank. Perhaps have four sessions of pumping for a half hour each, giving a total of two hours, which would turn over your tank once overnight. In particular, this should help maintain some water movement within the tank.
4. DWC Water Temp Control
The water in DWC bucket absorbs heat, raising the water temperature. Once the temperature of water gets above 68–70 degrees, plants run a very good chance getting root rot. Nothing worse than seeing the brown slimy roots eventually killing your plants. In summers with 90 degrees outside, water in the bucket placed in a room or outside will warm up.
If you are just using 5-gallon buckets or less, you may be alright depending on air temperature near your water. If you are using a big container or bed with of water, the best investment you will ever make is a water chiller.
How do I make my own DWC system?
Bubblers are incredibly easy to assemble – just follow our instructions below.
- Cut a hole in the center of your bucket lid that will accommodate the net pot without letting it fall through. If you use the 14.4cm Heavy Duty Net Pot – which we recommend – your hole should have a diameter of 132mm. This will support the pot securely and eliminate the possibility of it slipping through at a later date. If you are using a different size pot cut the hole to suit but make sure that this isn’t too big. As your plant grows, its weight will increase and the possibility of the pot falling through the hole increases.
- Fill your bucket approximately 2/3 full with pH adjusted ½ strength nutrient solution. Position your air stone on the base of your bucket and attach them to an Air Infusion Pump using airline.
- Start your air pump. The right level of air infusion for successful DWC growing will cause your nutrient solution to grumble and churn with the volume of bubbles.
- Transplant a rooted cutting into the net pot using clay pebbles as your growing medium.
- Replace the lid of your bucket and insert your net pot (containing your cutting) into the hole.
- At the beginning stage, the plant will need hand watering until its roots grow down into your nutrients. Once this has happened (usually within the first week) you will no longer need to hand water the plant.
Best DWC Systems in the market
|5-Gallons Deep Water Culture Kit|
Check Price Here
|4-Buckets Deep Water Culture Kit|
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|3.5-Gallon Deep Water Culture System|
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|6-buckets DWC Hydroponic System|
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|8-bucket Deep Water Culture Kit|
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There are some fully automated indoor hydroponic kits using which you grow plants easily and quickly. Read more about these hydroponics indoor kits here.
The major choice you face is when to drain. This will mainly depend upon the quality of your raw water, especially its sodium chloride (NaCl) content. Because of the very high volume of solution per plant in your system, it should take a long time before it would be necessary to drain. If the sodium content is under 23 ppm, then you may never need to discard. The higher the ppm Na, the quicker it builds to unacceptable levels.
As you suggest, trying to discard the full volume of grow tank is basically unworkable. You obviously can’t lower the level in the grow tank, so you would need to pump through to displace the old contents with fresh nutrient solution (not straight water). To even be a possibility, this would require automatic EC control in the control tank. Even then, this gives a huge volume to handle, plus the flow through the grow tank would not be ‘plug flow’, but there would be some mixing of old and new solutions.
This leaves the only feasible option to be ‘bleeding’. That is, taking off a small proportion of the overflow on a continuous basis. This happens unknowingly in many recirculating systems through leaks.
An occasional analysis would indicate how much you need to be bleeding. Try to maintain the Na level no higher than about 100 ppm in your recirculating solution.