This instructable will cover the build and operation of a deep water culture hydroponics system. So far, I have sucessfully grown banana peppers in this setup with complete ease since most of the process is automated.
Also, these plants were grown indoors completely under artificial light that outputs about 60 watts. The entire unit requires about 65 watts and runs for about 16 hours every 24 hours. It costs about 9 cents a day to run it.
When I first wrote this instructable it was about a month before I planted anything in it. Since then I have made many modifications to the hydroponics system such as a third light and a more advanced electrical system. I'm soon going to make a fabric cover for it with built in fans for air circulation. As a result you'll see some old and new pictures mixed together. Please bear with me untill I find enough time to re-write the whole thing.
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Step 1: Warning Science Content: an Introduction to Plant Physiology
To the naked or untrained eye, plants can appear as very simple and boring forms of life. In reality, plants are very complex creatures. In fact, genetically speaking plants are about twice as complex as humans.
They exist in two very separate yet two very interconnected and equally important worlds. There is the above ground world of the shoot system and the underground world of the root system.
The shoot system of the plant is what we normally see when we look at a plant in the ground. From figure 1B you'll notice that the shoot system is extensively branched to allow a maximum surface area for the absorption of sunlight. This part contains the leaves, which is where the chemical reaction we learned in junior high takes place:
6 CO2 + 6 H20 ==> 6 O2 + C6H12O6
This chemical process is known as photosynthesis in which the radiant energy from the sun is harnessed and converted into chemical energy in the form of sugars. Excess sugars produced by the plant can be stored in bulk, usually in the form of a fruit that is meant to provide a developing seed with energy until it can grow it's own leaves and manufacture it's own glucose.
The process of photosynthesis is actually much more complex than the above chemical reaction. It is really a series of dozens of chemical reactions that are only a small part of a plant's overall metabolism, which requires many other nutrients such as Nitrogen, Potassium, and Phosphorus. But how does the plant collect these nutrients? From it's root system.
The root system is responsible for providing the leaves and the rest of the plant with the required raw materials for metabolism and photosynthesis. From figure 1B you'll notice that the root system is extensively branched to allow a maximum surface area for adequate absorption of water and nutrients from the soil. Anything that is absorbed by the roots are transported up to the leaves through the plant's stem. In return, some of the oxygen and sugars produced by the leaves are transported down to the roots through the stem. The roots are not exposed to sunlight and therefore cannot manufacture it's own sugars.
There are three main problems with soil that limit the growth of a plant:
One is that soil does not contain a whole lot of oxygen that the roots need to survive. Roots need to "breathe" just like we do and this can cause a lot of problems when oxygen is scarce. Hydroponics systems help with this by delivering a highly oxygenated nutrient solution to the roots. This is most commonly achieved through the use of air pumps and bubblers similar to those used in aquariums.
The second problem with soil it that nutrients are often scarce and in a form not usable by the plant. For example, nitrogen in soil is often in the form of ammonia or gas and must be processed by nitrogen fixing bacteria before the plant can use it. Hydroponics systems suspend the roots directly in a nutrient rich solution that can be readily absorbed by the roots and used for growth.
Finally, soil can contain many pathogens that can lead to diseased plants. Hydroponics solutions can be easily sterilized to prevent any nasty creatures from infecting your plants.
By addressing these three problems, hydroponics allows plants to grow and develop at an accelerated rate. With all that being said, I finally give to you my design of an indoor Deep Water Culture (DWC) hydroponics system.
Step 2: The Deep Water Culture Design, Materials and Methods
Please refer to figure 2A for an illustration of the DWC system.
In Deep Water Culture (DWC) systems the plant sits in a mesh basket filled with an inert medium such as clay pellets. The inert medium does not provide the plants with nutrients but only acts as a support to anchor the plant down.
The basket is suspended in a reservoir filled with a solution of nutrients. As the plant grows, the roots will protrude through the holes in the basket down into the nutrient solution where they can be readily absorbed. (Figure 2B)
At the bottom of the reservoir sits an airstone hooked up to an aquarium pump. Air is bubbled through the solution and up to the roots to provide them with oxygen.
Although the leaves must be exposed to light, the walls of the reservoir must be opaque to prevent the nutrient solution from being exposed to light. Not only can roots be damaged by light but light in the reservoir will promote the growth of alge which is harmful to the plant.
The nutrient solution must be changed on a regular basis because the nutrients can be used up and "nutrient toxicity" can occur. Also, the pH of the solution tends to go up as the plants use up the nutrients. It can rise to extreme levels and end up killing the plant.
There are many versions of the DWC system available for retail but they are expensive and aren't DIY. I made mine from materials available at any Canadian Tire and Wal-Mart. Please note that I got the idea for the reservoir system from this build by trebuchet03 entitled Hydroponics - at Home and for Beginners.
I encourage you all to design your own DWC system, using this instructable only as a guide to expand and improve on my design. With that being said I will still provide a complete list of the materials I used below.
Lighting Frame and Supporting Structure:
3/4 inch CPVC pipe
3/4 inch CPVC tees
3/4 inch CPVC 90 degree elbows
1/2 inch CPVC pipe
1/2 inch CPVC tees
1/2 inch CPVC 90 degree elbows
1/2 inch PVC Conduit Boxes
PVC solvent cement
Electrical, Wiring and Lighting:
24 inch fluorescent light fixtures
24 inch fluorescent grow lights
18 gauge wire in black, red and green spools
A grounded plug that can be self-wired
Rocker switch rated for at least 125VAC at 1 amp
Vinyl shrink tubing
A firm knowledge of Ohm's law, circuit wiring and electrical safety
Aquarium air pump
Aquarium air tubing
Aquarium air bars
Air tubing shut-off valves
Nutrient Reservoir, Solution and Growth Media:
27 litre storage tote with lid
Can of black spray paint
5 inch mesh baskets*
Expanded Clay Pellets*
General Hydroponics FloraGro concentrated nutrients*
General Hydroponics FloraBloom concentrated nutrients*
General Hydroponics FloraMicro Concentrated Nutrients*
*For those of you that live in the St.John's, Newfoundland area, I recommend dropping by Grow Crazy. I got a lot of my materials there that I would otherwise have to get shipped in from the USA. The guy there is very helpful and there's a great selection of nutrients and equipment for any setup.
Step 3: The Lighting Frame and Support Structure
The main purpose of the lighting frame is to suspend the fluorescent light fixtures over the plants in the nutrient reservoir. I also designed it to be adjustable in hieght so that the lights remain only a few inches above the plants at all times. Also, I can hang some chicken wire or string from the top of the frame to help support the plant if needed.
The frame is constructed completely out of 3/4 inch CPVC pipe and fittings. There is also the 1/2 inch PVC electrical conduit boxes making up two of the top corners. These boxes house the on/off switch for the lights and all the electrical connections.
The top and the bottom portions of the frame are permanantly assembled with the CPVC cement. However, the vertical sections of the frame are not glued in. This allows the frame to be easily adjusted in height by adding or subtracting lengths of vertical pipe through the use of 3/4 inch couplings. The frame can also be easliy collapsed for storage or transport. (Figure 3B).
For some weird reason the 3/4 inch pipe fits almost perfectly into the 1/2 inch conduit boxes. However, I did have to sand down the pipe a tiny bit before it fit into the conduit box.
When cutting the pipe make sure you use a mitre block and deburr the pipe with sandpaper prior to glueing. Dry fit the pipes before priming and glueing.
The support structure is ment to hold the airbars in place underneath the mesh pots and to prevent the lid of the reservoir from sagging under the weight of the plants. It straddles both airbars and holds them far enough apart so that they line up underneath both rows of mesh pots. It is just the right hieght so that it holds the reservoir lid level. (Figure 3C).
The support structure is constructed of 1/2 inch CPVC pipe and fittings. You could make it out of leftover 3/4 inch pipe and fittings from the lighting frame but in my case the 1/2 inch fittings fit around the airbar better. I did not glue this one together, it holds together just fine without glue.
Step 4: The Electrical System
The electrical system consists of the three fluorescent lights, the two on/off switches, the plug, the outlet, the fuse and the wires. It allows the unit to be plugged into any standard wall outlet while the lights and auxillary outlet can be controlled by the toggle switches (Figure 4B).
Even though the light fixtures are ment to be celing mounted and wired directly into the house's electrical grid, I wired them with the plug so that this unit could be easily disconnected and then transported or stored. The use of a wall outlet for power also enables a standard programmable timer to automaticly control all of the electronics (Figure 4C).
This step is critical in terms of safety. If you wire this wrong or allow any exposed terminals to cross, you could start an electrical fire. An electrical fire could also result from using wire that is not rated high enough for the current and voltage loads that these devices require. Obviously, you also run the risk of getting an electric shock. MAKE SURE YOU KNOW WHAT YOU'RE DOING!!
Each of these lights require 120VAC and run at 20 watts. Using Ohm's law ( I = P/E = 20W/120V = 0.167A) I know that each light will draw a current of 0.167 amps. The lights are wired in parallel so that the voltage does not divide between them. This means that the main power cord will carry a current of 0.5 amps. The 18 guage hook up wire that I used was rated for a maximum current of 2.32 amps so it should be safe.
The wire came in a package with three colors. I used black for the live wire, red for the neutral wire and green for the ground wire. It is important to stay consistent with this or you could wire it up wrong and end up in big trouble when you plug it in and flip the switch.
When making connections, only splice a small portion at the top of the wire. Hold the two ends together and slip a wire connecter over them. Twist the connecter and youre done. Make sure you cover any exposed parts of the wire with electrical tape.
In the fluorescent light housing you'll find the live and the neutral wires coming out of the electronic ballast box. The ground wire should be connected to a metal part of the housing (Figure 4D) When you're looking at a standard north american wall outlet, the neutral hole is on the left, the live on the right and the ground on the bottom. This should be kept in mind when wiring up the plug and the outlet. Please note that a plug and an outlet face each other so the live and the neutral wires are on opposite sides(Figure 4E).
The main power cord runs from the plug into the main electrical box. This box is the main hub of power distribution for the electrical system. Inside, all like wires from the main power cord, the light power cord and the outlet power cord are connected in parallel. The live wire for the main power cord is interrupted by a 2 amp fuse before being connected to the other power cords. The live wires for the lights and the outlet are interrupted by a toggle switch before contuining to their respective loads (Figure 4F).
Three wires from the light power cord and three wires from each light run into the left conduit box (Figure 4G). From here it's just a matter of using wire connecters to connect all three wires of each color(Fighre 4H). **Please note that Fig 4H only shows the connections for two lights, I'll update soon!**
To make everything nice and neat I used electrical tape to bundle each set of wires from the lights and power cord. I used zip ties to secure the bundles to the frame. I also used a piece of shrink tubing to cover the wires running from the plug to the first conduit box (Figure 4I).
You'll notice that the entire electrical system is contained within the top portion of the frame. This allows the frame to be taken apart without having to disturb any wires.
When I first turned the unit on I monitored it very closely for hours. I inspected it frequently for signs of electric arcing or current overload. I also felt the wires every couple of minutes to ensure they wern't heating up. Fortunately, everything ran smoothly.
Step 5: The Nutrient Reservoir
The nutrient reservoir is built out of a storage tote and 5 inch mesh pots. The pots are nested in holes in the lid of the tote so that they are partially suspended in the nutrient solution in the tote. It allows for the plant's roots to grow down into the solution while the shoot system grows up into the light.
I picked the tote so that the lid would hold six pots in two rows of three. Four of the pots are located in the extreme corners of the lid and the other two spaced evenly between them. This maximizes the space between plants.
The pots are not prefectly cylindrical in shape. The radius of the top is bigger than the radius of the bottom. I traced out the tops of the pots on the lid of the tote and cut out the holes with a utility knife. The holes are sightly smaller than the traces so that the lip of the pot catches on the edge of the hole and does not fall into the reservoir. The reservoir must be deep enough so that there is a gap between the bottom of the pots and the top of the air bars.
When I bought the tote it was transparent. I coated the tote and lid with a can of black spray paint to prevent any light from reaching the inside of the reservoir. However, I think a roll of duct tape would work just as well or better.
Finally, two holes were drilled in the side of the tote as close to the top as possible. The air lines are run through these holes so that taking of the lid of the tote does not disturb the air lines (Figure 5C).
Step 6: The Aeration System
The Aeration System is set up to deliver a continuous, controlled airflow into the nutrient solution. It is made up of the air pump, air tubing, shut-off valves and airbars (Figure 6B).
The air tubing came packaged in a tightly wound coil. This was very cumbersome to work with because the tubing always tends to spring back into that shape. I let the tubing soak in a bowl of hot water for a few minutes and then stretched it out while it was still hot. When it cooled the tubing remained straight and was much easier to work with.
Between the air pump and the airbars, the tubing is interrupted by the shut-off valves. The rate of airflow into each airbar can be easily adjusted by twisting the knobs on the valves.
From the valves the tubing is fed through the holes in the side of the reservoir and into each airbar. the tubing runs through the side of the reservoir rather than the lid so that the lid can be removed without disturbing the air lines (Figure 6C).
Finally, the airbars are positioned so that they line up underneath all six of the mesh pots. From there they distribute air evenly to each plant (Figure 6D).
Step 7: The Integrated System With Room for Many Improvements
And there you have it, when you put everything together you end up with a freakin' awesome DWC hydroponics system.
However, I barely have it finished and I can already think of a few improvements to be made:
>Integrating the air pump's power cord into the electrical system so that it can be controlled via an on/off switch. (DONE)
>Painting the lid of the reservoir white so that it reflects light back up to the plant rather than absorbing it.
>Running all of the wires through the CPVC pipe for an even neater look.
>Adding a water pump to circulate the nutrient solution through a UV sterilizer to keep out unwanted organisms.
>Sewing together a fabric cover to slip over the frame and help keep out ambient light while trapping in growing light. (In Progress)
> Addition of a third growing light. (DONE)
> Adding solar cells, a battery bank and a power inverter to make it run on free electricity. (In Progress)
> And of course, expansion, expansion, expansion!
I will soon add some more steps on mixing the nutrient solution, testing and adjusting the pH, setting the light timer and eating fresh picked vegetables whilist up to my ears in snow!
Thank you for reading. I hope you enjoyed this instructable and I welcome any constructive feedback. Happy growing!
Step 8: Ok, So I Built the Thing....Now What?
Well now I have to grow something in it or else it would be a terrible waste of time and effort. Even though hydroponics is a relitively easy and sucessful method of growing, it still requires a signifigant effort and regular care and maintenence. The following steps should provide some insight into the things that need to be done to grow a plant hydroponicly.
But I can't do anything untill I have a plant to grow and the selection of that plant is important. Each plant has specific requirements that have to be met such as the pH of the nutrient solution, the size of the setup, the spacing between plants, the amount of light, etc. You should do your own research on any plant you may be thinking about growing hydroponicly. My first selection of plants were banana peppers for three main reasons:
1)I love spicy food and I like hot peppers as a topping on just about anything.
2)This is a fruit producing plant so I can test how adjusting the timing of the lights will affect the onset of the different stages of the plant's growth.
3)This plant produces it's fruit above the ground. I don't think plants that produce sub- teranian food like carrots and potatoes would be suitable for this type of application.
So in order to get the pepper I need to start with the seed. Read on to find out how...
Step 9: Germinating the Seeds
I've read a lot about how seed germiation is a complex and delicate process where only the most talented gardener can hope to have a 50% sucess rate. In my personal experience it was easy and I've almost never had a seed that did not germinate. You just need a few simple materials that are easy to obtain from any department store around spring and summer.
The main requirements are (Figure 9A and 9B):
>A humidity dome. This is basically a mini greenhouse that allows sunlight to enter and keeps moisture in. A developing seed's worst nightmare is drying out. These can be bought for pretty cheap but I've used cake domes and chicken domes before and they worked just fine.
>Rockwool cubes. It's just a piece of fibreglass-like-material with a hole in the middle. They hold in moisture well, are breatheable and allow the rootst easily grow through them. Peat pellets work great too but are not suitable for hydroponics setups.
>Some plant food. There's all sorts of fancy and expensive formulas especially for starting seeds but I just use the good ol' general purpose plant food. Just mix it with water in a spray bottle and use it whenever you water the plants.
Start by soaking the rockwool cubes in the plant food solution for a few minutes. Remove them from the solution and lay them in the bottom of the humidity dome. Drop a seed into the hole in the cube. Place the lid on the humidity dome and leave it in a sunny location indoors.
The seeds will need to be watered daily. A lot of condensation will collect on the lid of the dome. I just shake the condensation into the sink and mist the cubes a couple of times. Repeat this as long as they are inside the dome.
When roots are protruding from the bottom and sides of the cubes and they have developed a pair of secondary leaves, they are probably ready to be transfered to the hydroponics system (Figure 9C). It is now time to disinfect the nutrient reservoir and fill it with nutrient.
Step 10: Disinfecting and Filling the Reservoir
The Nutrient Reservoir can become quite a utopia for all sorts of nasty microorganisms that can wreak havoc on your plants. If I've only learned one thing from my years working in microbiology labs it's that they are persistent little buggers. If you give them half a chance they will take over your entire setup in no time flat. There's no way that you can completely suppress them, but you can prevent them from flourishing with a few simple preventative measures.
First of all, the reservoir and growth medium has to be disinfected prior to use. All you need is a bathtub, some hot water and some chlorine bleach. The clay pellets a covered in dust before their first use so I rinsed them off before filling each mesh basket with them (Figure 10B). I laid all six mesh baskets in the empty reservoir and then added a generous portion of chlorine bleach. I filled the reservoir with hot water and let the whole thing sit for about an hour. Then I gave everything a quick rinse and it was ready to be filled.
The water level here is important. At first the roots probably won't be sticking out of the rockwool cubes so you should fill the reservoir up to soak the cubes directly. As the roots grow down it is necessary to lower the water level until there is a small gap between the surface of the water and the bottom of the mesh pot. The roots should have to pass through a small air space between the pot and the solution.
Now to prepare a good nutrient solution, a few skills in mathematics are required. Most hydroponics nutrients come in a very concentrated form that must be diluted before the plant can use it. The bottle should give you an amount of nutrient to mix with an amount of water (Figure 10C). As you can see the nutrient comes in three parts that must be mixed in different proportions depending on the stage of the plant's growth. The bottle only lists how much of each nutrient to mix with 100 liters of water. Since my reservoir does not hold that much I need to come up with an equation that generalizes how much I need to add to any volume of water.
Vn = (Vr/100L) x Vb
Vn = Volume of nutrient needed (ml)
Vr = Volume of water in reservoir (L)
Vb = Volume of nutrient per 100L as listed on bottle (ml/100L)
For example, when I first filled my reservoir I used 14 liters of water to accomidate my plants through the vegetative growth stage. The amount of nutrient listed on the bottles were:
FloraGro: Vb = 396 ml/100L
FloraMicro: Vb = 264 ml/100L
FloraBloom: Vb = 132ml/100L
Therefore the volumes of nutrient I had to add to my reservoir were:
FloraGro = (14L/100L) x 396ml/100L = 55 ml
FloraMicro = (14L/100L) x 264ml/100L = 37 ml
FloraBloom = (14L/100L) x 132ml/100L = 18 ml
Of course, all of these volumes have to be measured accurately. For the water I used a measuring cup and for the nutrient I used a syringe. A pen, some paper and a calculator also comes in very handy when doing this task (Figure 10D).
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