What is Deep Water Culture (DWC)? – A-Grade Hydroponics
Deep water culture is a soil-less method of growing plants.
Rather than growing in soil, you use a large reservoir containing a nutrient solution. The nutrient solution must be aerated (oxygenated) for it to be truly effective hydroponic system, this is usually achieved with the use of an Air Pump and Air Stones.
The plants root-zone is partially suspended in this aerated solution, as roots need oxygen to form.
The plant uses capillary action to transport nutrients, the air contained within the nutrient solution is vital for the root zone to form properly.
HOW CAN DWC WORK FOR ME?
DWC growing can be done indoors and out.
Whether using a system with 24-sites or just one, you will be able to root cuttings using this application, or just grow a single plant into a monster.
Whichever style you choose, because of the systems versatility it can be modified to suit any project very easily, and quickly.
DWC & TEMPERATURE
Temperature in any form of gardening is something we are all aware of, the same applies to DWC growing.
Our reservoir will have a Min and a Max for temperature, exceeding either of those windows can result in health problems for your plants.
To help maintain correct temperatures, we advise changing your reservoir’s nutrient solution every 2-4 weeks.
While DWC growing does require some maintenance and monitoring, if your setup falls outside of the optimal temperature ranges for short periods of time (few hours), your plants should be fine, if you leave your plants for days without adjusting temperature issues, you will start to see problems arise.
Water temperature ranges for DWC systems:
The perfect range; 15C – 21.5C (65-70F)
Temperatures 15C or lower, and the plants will go into shock, the drop-in temperature will cause cellular activity to stop, rapidly declining plant health.
Temperatures 21.5C or higher, will result in the level of (DO) Dissolved oxygen to go much too low for the plants daily requirements, at this temperature or higher more worrying things like pathogens and root diseases form rapidly.
DWC & pH (Power of Hydrogen)
As with most indoor gardening methods, plants generally uptake nutrients when all factors are in place.
Let’s talk briefly about pH:
Regularly checking your pH level informs you whether or not your plants can consume food.
Plants absorb nutrients when the pH of the nutrient solution is in range.
Most plants hydroponically grown, will grow perfectly between the pH range of 5.5 – 6.5
If the pH range goes outside of that suggested window, then some nutrients will become “unavailable” to the plant, resulting in deficiencies and growth problems.
To correct these decreases in pH, we can do a few things:
To lower the pH, we can use a product called pH down. This is basically an acid, by adding a few drops we can change the pH.
We can also add more of the base nutrient (food) and this will also lower the pH, in hydroponics this is generally the go-to method.
To correct these increases in pH, we can do a few things:
To Increase the pH, we can use a product called pH up. By adding a few drops we can increase the pH.
We can also dilute our solution by removing 5L at a time and re-adding the appropriate amount of water to dilute.
DWC & EC (Electrical Conductivity)
Regularly checking your EC level informs you of how much food your plants have available to them and whether or not they can consume.
Plants absorb nutrients when the pH of the nutrient solution is in range.
Most plants hydroponically grown, will grow perfectly between the pH range of 5.5 – 6.5
If the EC range goes above of the recommended number, then some nutrients will become “locked out” to the plant, resulting in poor growth and deficiencies and/or toxicities.
RESERVOIR CHANGE
A lot of gardeners new to hydroponics often ask how long until they should change their nutrient solution.
There are many opinions on this topic so ill will keep it brief, realistically the whole concept of hydroponics is to grow without soil and save water?
Changing our nutrient solution on a weekly basis doesn’t seem very economical in regards to nutrient outgoings or promotion of water savings.
If your plants are healthy and your nutrient solution is being consumed evenly (pH & EC readings stay even) as the water level drops we should just be re-adding the lost volume.
So, if your starting reservoir capacity is 40L and each day your find your plants are consuming 4-6L of nutrient solution & water evenly, then we need to make up a fresh mix of the depleted nutrients & water to re-add to the reservoir.
Never fill your reservoir right up to the base of the net pot, roots need oxygen so fully submersing them in water will only suffocate the plant.
Ideally, you would have the solution about 3-4 inches below the base of the pot, this will allow excess oxygen & humidity to aid in fast root development.
BUILDING YOUR OWN DWC SYSTEM IN 10 STEPS
Here I will share all of the items you will need to create your own deep water culture system using a common DWC design.
First things first, you will need these tools:
- Drill
- 4mm Drill bit
- 140mm Hole saw
Next up is our required materials:
STEP 1 – Place Lid on tank securely, attach hole-saw plate to drill, start drilling your required number of pot holes. I’d recommend starting with just 1 per tank.
STEP 2– Attach 4mm Drill bit to drill and drill two holes in one side of the tank under the lip approx. 10cm apart, Remove excess plastic dust and clean tank.
STEP 3 – Thread desired length of 4mm airline through holes roughly towards the center of the tank then attach the air stones to the ends.
STEP 4 – Attach the other ends of the airline to the outlets on the Air pump, DO NOT plug it in just yet.
STEP 5 – Fill up reservoir with required amount of water – for 52L tanks I recommend 35L and for 68L tanks I recommend 45L
STEP 6 – Add the required amount of nutrients & Root tonic to the water.
STEP 7 – Transplant seedling or cutting into 140mm mesh pot and cover over with the pre-washed Hydroclay stones (This will help root growth and also prevent light from entering the reservoir, which can cause many problems)
STEP 8 – Turn on Air Pump and turn dial up to around 75%
STEP 9 – Using the freshly mixed up solution, fill a jug with the mix and top feed the new cutting.
STEP 10 – Check pH and EC of nutrient solution to double check all of your numbers are correct and within range.
Now you are good to go in your brand new deep water culture system!
Happy growing, please submit comments below if there are any questions I haven’t covered.
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