Welcome to the Beginner’s Guide To Do-It-Yourself Hydroponic Deep Water Culture Systems. This article will run you through the process of making your own 8 plant DWC system from a 10 gallon plastic tote/bin you can find at your local walmart or elsewhere. This article assumes you know nearly nothing about hydroponics and is intended for beginners or experts who are interested in making their own 8 plant DWC rig. Let’s get started.
What You'll Need:
- 10 Gallon Plastic Stacker Storage Tote
- 8 Net Cups (4")
- Air Pump (3.2 Liters Per Minute)
- Circular Airstone w/ Suction Cups
- Power Drill + 4" Bi-Metal Hole Saw Attachment
- Kitchen Sink Strainer Washers x8 (Optional)
- Hydroponic Nutrients
- pH Control Kit
A DWC is a type of hydroponic system where the plants are placed into small netcups, surrounded by hydroton, and then suspended above a reservoir of water. The roots grow down from the netcup into the reservoir, allowing it to drink nutrient rich , aerated water.
In this tutorial we are going to teach you how to build your own DWC system, pH correct your water, and then add nutrients to your system. We will also cover how to properly aerate the water so that the roots get the right mix of food, water, and oxygen that they need to thrive. This is a front-to-back tutorial that will help someone completely new to hydroponics build a compact DWC system for the purpose of growing small plants such as lettuce, spinach, basil (or any herbs) etc.
Let’s start with building the system itself, we will discuss the other aspects of it along the way. Here we go!
PART 1: Drilling The Holes In Your Container
Start with a container like this. You can substitute this for a 20 gallon container or anything else as long as it has a lid and a place for an adequate amount of water.
Plan out where the netcups will go:
Get your power drill with a 4″ hole saw attachment:
Mark the center of each netcup on the lid with a permanent marker:
Begin cutting hole in the lid:
Place your 4" netcups in:
TIP: When cutting out your holes, you will have leftover plastic inserts the size of the hole you cut. Keep these for later, we'll discuss why a little further down.
PART 2: Install Airstone
Drill a small hole above the water line for the air hose:
Insert airstone and connect the hose:
PART 4: Adjusting The pH Of Your Water
It is important that our water has the correct pH before we proceed, as having the correct pH will allow our plant’s roots to uptake nutrients and stay healthy. Most water, be it tap or reverse osmosis, comes by default at around a pH of 7. This is a bit too alkaline and plants prefer more of an acidic environment. The optimal pH range for hydroponic cultivation of nearly every plant type is 5.5-6.5. So in order to dial down the pH a bit, we are going to use some pH Down chemicals from General Hydroponics. Once we have added our water (this particular system requires 5 gallons), we can adjust it’s pH level down by putting no more than 3 drops of pH down chemicals into the water itself, using either an eye dropper or any other device capable of administering only a single drop at a time. These chemicals come very concentrated and a single drop or two is usually more than enough. To test the water again once you have added your pH down chemicals, use a Digital pH meter or pH testing kit to determine what the pH level is. By now it should be around 6.0. Optimally, I would say shoot for a pH of 5.8-6.0, but again the acceptable range is 5.5-6.5. For a more in depth video on how to adjust the pH of your water, check out our friends over at Epic Gardening who have put together an excellent video guide to correcting pH and adding nutrients to your water. They also did a nice review on the best digital pH meters.
PART 5: Adding Nutrients
There is a wide variety of hydroponic nutrients available on the market today, I've tried many and in my opinion the best one for begnners is the GH Flora Series. It comes in a 3 part system (Grow, Micro-Nutrient, Bloom), and this is great because we can adjust what nutrients we are giving the plants based on what period of growth they are in and what type of plants we are growing. For a tomato plant you would start out with Grow+Micro, then as it becomes time to flower and produce fruit, you switch over to Bloom+Micro. For the purpose of this tutorial, we are growing small, non flowering plants such as lettuce and spinach (or any herb like basil etc), so we will only be needing the Grow and the Micro Nutrients, as our plants will not be flowering at any point in their life cycle. Here's what the nutrients look like:
When it comes to nutrients, you can pretty much follow the directions on the bottle and achieve great results. Once you get more advanced, you will learn to eyeball it and know how much of what nutrient your plants need, but for now we will just follow the label’s directions as that will work 99% of the time. For this particular nutrient, it requires 1 tsp of grow nutrient for every gallon of water, and 1/4tsp of micro-nutrient per every gallon of water. The two must always be used in conjunction as the micro-nutrients help supplement both the grow or the bloom nutrients and are important throughout all stages of plant growth. So go ahead and follow the direction on the bottle and keep in mind that we are using 5 gallons of water in this system, and mix accordingly. All you need to do is take a tsp and measure out your grow nutrients (in this case 5 tsp), and put it directly in the water, then add your micro-nutrients (in this case 1.5 tsp) and throw it in the water right after. Boom, you’re done adding your nutrients, now just give the water a good stir so it is evenly dispersed and you are goo to go. If you have a a TDS pen, you can check the PPM of your water to see how concentrated the nutrient is, for a system like this we would be looking to have a PPM of ~700. For a more in-depth explanation of what PPM is and what it means, check out our article on “TDS, PPM, EC & What They Tell Us“
You could stop right here, because that is all the plant really needs to grow, but there are a few extras I always include in my feeding regiment which I have had great results with, so I will include them here for you too.
The first one that I include in EVERY hydro system I operate is some sort of calcium/magnesium supplement. The popular ones are CalMag+ and CaliMagic (but frankly even some epsom salt will work if you’re in a pinch).
What it is: CaliMagic is a calcium and magnesium supplement. This is of particular importance if you are using reverse osmosis water. Water that has been run through an R/O filter has been stripped of virtually all trace elements; of minerals, metals, chemicals etc. This is good in many ways, but one thing our plants need is calcium/magnesium. So since we are using R/O water, we have to essentially re-introduce the calcium/magnesium into it so that it is at the optimal levels. If you are growing tomatoes for example, a calcium deficiency will result in fun things like blossom end rot, and on basil it will result in grayish leaves that do not look appetizing. This supplement is a must in all hydro systems as far as I am concerned. I did not use it for a long time but learned my lesson, so you would be smart to just begin using it right off the bat. If you are using water straight from the tap, than there is a good chance that it already has a bit of calcium/magnesium in it to begin with, so this supplement may be less necessary. However, I would still add it even if I were using tap water, just maybe at a lower dose.
Next on the list are root boosters, here are my favorites:
Clonex: This is a supplement which will help your roots grow big and strong. It is primarily used to improve already existing roots, as opposed to making new roots emerge, but I always begin using this right off the bat in any of my systems and continue it’s use throughout the growth cycle. Remember, roots are the lifeblood of the plant, so if anything you are trying to grow good strong roots, because good strong plants will be the biproduct. If you can get beautiful long white roots, than everything else pretty much handles itself. Add in 2tsp per 5 gallons of water for this supplement.
Bio Root: This is similar to the Rapid Start, but it focuses more on developing new roots rather than strengthening and growing existing root systems. This supplement is something you want to use in the early stages of your grow cycle to encourage the development of new root growth. In fact, if you are starting from seed in something like a Rockwool cube, add a little of this into the water you spray your cubes with in order to stimulate root growth as soon as possible. For this DWC system, add 1tsp per gallon of water.
Both of these are optional, but they do work and if you do decide to use them, they can both be used in conjunction with one another throughout the entire grow to make sure your roots are always in top shape. Because we like root porn around here, I will show you an example of what these two amazing supplements can accomplish (these are from some basil plants I have in another DWC)
That’s after only a few weeks of growth, so if you can afford it, use these root boosters to get long sexy and white roots like these.
PART 6: Final Touch Ups
When we cut our holes, we used a 4 inch hole saw. Since we are using 3.75 or 4 inch netcups, this seemed ideal, however while the netcups will sit snugly on top of the holes if left undisturbed, they will slip through the holes and into the reservoir if any extra weight is added. This is something youdo NOT want happening once you have a plant in your system, but fear not for there is a cheap and easy fix to this problem. Go to your local Lowes, Home Depo etc and find some Kitchen Sink Strainer Washers, they are little rubber pieces about 4 inches in diameter that look like this:
What we are going to do is fit one of these onto each of our netcups for extra support so that once we get a plant and some extra weight into the netcups they will sit flush with the surface and not fall straight through into the reservoir. Put them around your netcups as shown in this photo:
Now when we place our netcup into the system it will stay in place and be firmly supported as seen here:
Place each cube in the center of the netpot and fill it with hydroton so that it is properly supported, as seen in the photos below. Make sure there is a thin layer of hydroton directly beneath the rockwool cube so it doesn't sit at the bottom of the netcup constantly soaking up water. Sometimes starving them from water a little bit is what gives them the push to grow those roots down into the reservoir where we want them. Fill it up to the top of the rockwool cube as seen in the below pictures.
Remember when I told you to save your plastic cut-outs from when you were drilling your holes? This is why. They are great to use as a cover in case you decide to remove one of your plants, or in this scenario where I am waiting to put a basil clone into the final empty slot. This will help keep light out of the system while you are getting everything ready to fill the space. Just be sure to put some duct tape or something over the hole in the center so that no light gets through. Here are some more pics:
So that’s it, you’re done. You've built (from scratch) a DWC container, fed it with a airstone, added pH corrected water and dialed in your nutrients. At this point you can either put it outside and let the sun do it’s thing, or you can keep it inside under some lights. If growing indoors with lights, I recommend a set of T5 horticulture lights with a reflective holder as it is only about $100 and is the exact size you need for this system. If growing indoors, keep the lights about 4-5 inches from the tops of the plants.
FINAL STEP: Paint Your Reservoir To Block Out Light
The last step is to now spray paint the translucent part at the bottom of the container. The choice of color doesn't really matter, and many use black, but keep in mind that if you are doing this outdoors the black color will insulate heat and you want the temperature in your reservoir to be <80 degrees at all times. Temperatures over 80 degrees coupled with light coming in through the container will result in bacteria and other unwanted things growing in your reservoir, so make sure little to no light is getting through. If it does get hot and you are doing this outdoors, just take a few bottles of water and freeze them each night, and then when you leave for work the next morning be sure to drop them in the reservoir. They should do a decent job of keeping the water under 80 degrees.
You aren't going to have to do much maintenance, but there are a few things to keep in mind. At first, your plants won’t have big long roots because they are still just babies. Because of this, for the first week or two you will want to hand water them from the top, using water you took from the reservoir, to make sure the hydroton and the rockwool cubes stay moist. Eventually, the roots will find their way down into the reservoir and once they have access to that 5 gallons of nutrient, oxygen rich water they will begin to explode with growth. The water level upon starting out should be right to where it is touching the bottom of the netcup, but not submerging it. As time goes on and your plants grow roots, the water level will lower and the roots will lower with it, until eventually they have crawled all the way down to the bottom and are just basking in the optimum mix of water, nutrients and oxygen. Once the roots get bigger, you would ideally want the top part of the root suspended in the air with no water on it (so it can breath), and the bottom of the the root system completely submerged in the water. By doing this, you’re roots get the optimum amount of oxygen and nutrient rich water.
You should check your pH levels daily, and make sure that it stays within the acceptable range (5.5-6.5). You MUST check it at least every few days. Use your pH up and pH down chemicals to keep it within the range, this is probably the most important part of the ongoing care. In a larger reservoir, you may only need to check the Ph one every 2 weeks, but in a reservoir this small, pH can change rapidly so you must be vigilant and check it frequently if you want your plants to thrive.
Another thing to keep in mind is that bacteria and disease will grow in your reservoir after a period of time, since it’s a nice easy place for them to get lots of free food, water, and humidity that they love so much. Because of this, it is advised that you dump out you reservoir every 2 weeks (some do it every week). This is mandatory and must be done, even if all is looking well. Just dump it out (preferably not down a drain), and refill it with pH corrected water and nutrients. Keep doing this every 2 weeks throughout the life cycle of the plants. If you notice anything growing in your reservoir, or a nasty bacterial sort of smell, you can treat it with a SMALL amount of hydrogen peroxide. Use the kind at the store used for mouthwash or an anti-septic and place a few tablespoons in there. Really you should not do this unless absolutely necessary, as you will inevitably see evolution in action and notice that only the peroxide resistant bacteria survive, so use it sparingly. For the record, I have never had to do this in any of my systems, so you should not either unless things get really bad.
So there you have it, you’ve built your own 8 site DWC bucket and are ready to produce delicious food year around.
For a move detailed, step-by-step version of this tutorial, check out my video: The Beginners Guide To Making Your Own 8 Site DWC, as seen below.
Update: Day 2
It’s only been 2 days and already the roots have grown down into the reservoir, and we are beginning to see the leaves grow at an accelerated pace. Keep in mind, I have not painted my system ONLY because I want to show you pictures of what is going on under the hood. Your system should be blacked out so no light gets in.
Again we see a near doubling of the root size in only 1 day since our last pics: