Mini DWC Grow System
Deep Water Culture (DWC) is a popular hydroponic system and need not be done in a 5 gallon bucket or large tote as most of you do. It may be carried out in a much smaller container for those of restricted space or those wanting to grow many varieties of marijuana at once; or to either carry out experiments, or to choose a superior phenotype for use as a mother plant.
All of the same rules apply as to growing in a standard bubble bucket with a few obvious limitations:
- Marijuana grown should be switched to flower (12/12 lighting cycle) very early; anywhere from seed to no more than three weeks maximum;
- Because the reservoir is limited in space, it will need to be checked and topped regularly. During mid to late flowering it might require daily topping;
- Cleaning the container and changing out the entire reservoir will need to be done much more frequently. I would suggest weekly as the plant matures although going two weeks is unlikely to cause harm.
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I started with the standard DWC equipment:
- Small air stone
- air pump
- 3’ of ¼” clear vinyl tubing
- 2” net pot
- media – lava rocks
- reservoir – a half gallon plastic coffee container
Advantages of the plastic coffee container is that it has a built in handle, making it easy to change the reservoir or move about unlike a 5 gallon (or larger) DWC. This size allows for many plants to be grown in a small area though maintenance can be a bit much for more than a handful of plants.
- I started the Northern Lights seed (henceforth known as ‘Ginger’) in a peat pot and then cut a hole in the lid of the coffee container for a 2″ net pot. If I were to repeat this experiment I would paint the lid black as it is translucent and may cause algae problems later though I experienced no such issues;
- The peat puck was placed in the net pot and covered with lava rock.
- She was then placed under a 24W (13W actual draw) red & blue LED spotlight. An aquarium air pump and air stone were added. Nutrients used were QuickGrow nutrients, dry at 1/4 strength dissolved in hot tap water and then allowed to cool.
This is a 36W E27 base with 8 red and 4 blue CREE 3W emitters sourced from E-Bay/China, they cost only about $25 each. Actual power draw is about 18W. It is certainly bright enough, but the focus is not right as the lighted area is very uneven.
Here is picture-perfect Ginger (Northern Lights) at about 10 days from seed. Note that I underfeed my plants and they seem to be much healthier and happier for it; i.e. zero nutrient-burn.
I put Ginger into flower a few days later under my 165W DIY CREE-based LED, but I waited a bit too long as the roots easily filled up the container later on in the grow. Other than more frequent maintenance, the whole flowering process was fairly routine.
Here she is adjusting to her new environment quite well at about 3 weeks just before she started stretching for the sky.
I grew the plants pictured purely as an experiment to see what the lower limit was. Remember that this reservoir was only 1/10th the size of a standard 5 gallon reservoir. While a grower could go smaller still, it would become quite impractical.
It worked surprisingly well, but is not very useful for anything beyond experimenting or for growing a small personal stash. As you can see I burnt the top a little. The yield is about 1.5 ounces dry weight. Here she is at 26” tall (a bit too much!) and 1-2 weeks from harvest.
This is too large for this container as she can barely ‘stand’. There is not enough media to adequately support such a weight. Interestingly enough, Ginger (Northern Lights) was over twice the size of her sisters started at the same time with the same seed stock and grown in one gallon (twice the capacity), hand-watered, passive hydro.
Because of the amount of maintenance involved and inherent limitations, there are better options for growing many small plants hydroponically, usually referred to as a SOG (Sea of Green) style of growing.
That being said, if I wanted to use what I learned from this for a commercial grow, I would design an array of interlinked 4” to 6” diameter vertical PVC pipes, maybe 18” in length, to allow for long roots and a much more stable base, and switch to either a recirculating top-drip or flood and drain hydroponic system.