Compact, Cheap, and Expandable Hydroponics System





Introduction: Compact, Cheap, and Expandable Hydroponics System

I know there are a ton of other instructables out there that deal with hydroponics but I wanted mine to fulfill a certain set of specifications. When I sat down to design my new hydroponics system for my apartment I had a few goals in mind. The system had to be cheap, since I'm on a college kid on a college budget. The system also had to be expandable, just in case I wanted to add some new plants. I really liked the ebb and flow system since it can be powered by a cheap aquarium pump and does not have to run constantly. I thought of every-day, cheap, household items that I could use for the containers in an ebb and flow system. I also needed to be able to construct everything with very limited tools. I only had a dremel with various attachments, some pliers, and wire cutters. As a result, I came up with a complete ebb and flow system consisting of a three container system and pump for around $20. If more containers were desired, it would only cost around a dollar per container.

I wanted the system to be expandable but I was also pressed for space since I am living in a very small apartment with three other individuals. The final parameters were: the system had to be easily managed and easily transported. Easily managed because I'm sometimes lazy when it comes to upkeep and easily transported because the system is not going to be set up in a permanent residence; I will be moving at the end of the semester. Since my apartment receives very little lighting I decided to make a grow light stand as well. Since grow lights can get up into the hundreds of dollars, this adds quite a bit to the total cost of the project. Although this allows you to put your plants where ever you please, it is by no means necessary as long as you have sufficient lighting.

Step 1: The Containers

The main focus of this project is on the containers. I chose the screw top Ziploc containers for the reservoirs because they formed an airtight seal but could be easily opened easily when the nutrient solution needed to be changed. The Ziploc brand containers were $2.97 for three. There are also generic brands out there that I have seen for around $2.00. For the actual pot I used the top of a 2-liter. I used these because they can usually be obtained for free. To power the system, an aquarium pump and some tubing is used. To keep the system automated, you can purchase cheap lighting timers from your local hardware stores. The complete parts list is below.

Initial Setup:
1 x $3.00 - 3 Pack of Ziploc Screw Top Containers
1 x $1.50 - Length of Aquarium Tubing
1 x $5.00 - Aquarium Pump
1 x $5.00 - Light Timer
1 x $3.00 - Silicone Sealant
3 x $0.25 - Rubber O-Ring
3 x $0.55 - Straight Connector
3 x $0.00 - Empty 2-Liter

Total: $19.90
~ $20.00

Three Addition Containers:
1 x $3.00 - 3 Pack of Ziploc Screw Top Containers
3 x $0.25 - Rubber Washer
3 x $0.55 - Straight Connector
3 x $0.00 - Empty 2-Liter

Total: $5.40

To make the 2-Liter containers look nicer I scrubbed all of the glue and label off. If you've ever tried to do this for other projects, it's quite a hassle. An easy way to clean the 2-Liters off is to fill them up with hot water and cap them. Next, submerge them in hot soapy water and let them sit for a few minutes. You should now be able to scrub the label/glue off with a coarse dish scrubber as shown in the pictures. The glue and label free tops can now be cut off.

To start the construction of the containers I traced the 2-Liter onto the lid and started to grind away with my dremel. It is important that you get close enough to the size of the 2-Liter while not cutting too much or too little plastic away. If you don't get a big enough hole, the lids will crack when you try to screw the 2-Liter in there. If the hole is too big, you will need to patch up a lot of space. I found these #18 O-Rings at the hardware store. They fit nice and snug around the 2-Liter. The caps need a hole for the aquarium tubing to fit through and the tube has to reach all the way to the bottom of the reservoir. When the reservoir is pressurized, the nutrient solution will be forced up into the plant. To put it all together I fit the O-Rings on the 2-Liters and screw them through the lid, applying silicone sealant to the base of the threads. I then fit the cap on and tighten. You should also smear sealant where the aquarium tubing goes into the cap to prevent an air leak. Next, the straight connectors are cut in half and holes are drilled for them. Sealant is used here as well. Remember that one of your containers will only need one port while the others will need two to pass the air pressure on.

Step 2: The Light Stand

I wanted the light's height to be easily adjustable so as my plants grew, I could raise the light accordingly. To make it as simple as possible, I used PVC tubing and PVC connectors. The stand costs around $8. I found a modestly priced 2 foot grow lamp for $27 at a local hydroponics store that provided ample lighting for the plants I was planning on growing.

Light Stand Parts List:
2 x $2.50 - 10 foot lengths of 1/2 inch PVC pipe
4 x $0.25 - 1/2 inch T connectors
4 x $0.25 - 90 degree connectors
1 x $1.00 - length of chain to hang light

Total: ~$8.00

The first step in the construction involves cutting all your PVC parts to length. I roughly estimated the length needed for my 2 foot grow lamp. Once all the parts are cut, the stand is assembled. My grow light came with some hardware to mount the light to a flat surface such as a wall. I wanted to hang mine from my stand so I unlinked some chain and wrapped it around the stand and the brackets. To provide adjustable light height, the legs can move from straight up and down to spread out. Since the grow light wasn't heavy, I didn't have to worry about the legs of the stand flattening out. The pictures show how the adjustable height works. My light also came with a convenient expansion feature. The connector pictured below allows you to add another light to the setup that will use the power from the original light. I built two sets of legs, one short set (for germination of new seeds) and one long set (for full sized plants). Germinating seeds will not need light while sprouting but once they start to grow, they will need plenty of light to get going.

Step 3: Info and Tips on Getting Your Garden Started

Ebb and flow systems work by flooding a nutrient solution to the plant roots 2-5 times a day. After a nice bubbly soak, the nutrient solution drains away. I have run an ebb and flow system using just plain tap water and some liquid miracle grow fertilizer as the nutrients. Although it worked, I wanted to increase the rate of growth and yield. I did a bit of research and reading about the main aspects of hydroponics.

Nutrients and pH
I bought this nutrient solution ($11.95), as well as this pH tester ($4.95), at a local hydroponics supply store. The nutrient solution is mixed according to the label and put into the reservoirs. The solution will need to be changed EVERY TWO WEEKS! Failure to change the solution can result in the production of chemicals that are toxic to your plants. This will poison and kill them. Depending on the size of the plants, the system should be "flooded" 2-5 times a day for 15-30 minutes. Be aware that many nutrient solutions come with two or more parts that are mixed in different proportions depending on if your plants are in the growing stage or the budding/flowering stage. The nutrient solution I bought is just for growing since I am growing cilantro, parsley, basil, and thyme and don't want the plants flowering and creating seeds. The pH tester was just a few dollars and is nice to have. If the plants start to deteriorate, the pH can be tested to see if that is the underlying problem. If the pH is fine, you know it has to do with something else. The pH should not be a problem if you buy a nutrient solution since the solutions are designed to have the correct pH for growing.

Lighting and Temperature
If you are using artificial light, another timer should be set to give the plants around 14 or 15 hours of light a day. While seeds are germinating, there is no need for sunlight. However, once the seeds sprout, they will need plenty of light to grow. I also bought a thermometer to monitor the temperature. Many plants have ideal growing temperatures and this cheap, $1.00 thermometer is a good tool to have and will help you monitor the ambient temperatures in your growing area.

Getting Started and Tips
I am using expanded clay ($9.95 for 10 pounds) in my system. The clay pellets rub together in transit to stores and produce a fine powder. They should be washed before use. Before transferring plants into your system, make sure there are no leaks by doing a quick test. I saved one of the bottoms from a 2-Liter to act as a stand when changing the solutions. The more containers that are used, the bigger the pump that will be needed to keep the flooding process going at a reasonable rate. A smaller pump may work but it may also take 10 minutes for all of the containers to flood completely. Also, be sure to check for leaks in your pots. One small leak will greatly reduce the air pressure in your system and drastically slow down the flooding process. One benefit of an ebb and flow system is that the roots of the plants do not grow to be very large since the nutrients is delivered directly to them. This allows for smaller pots and a more compact design.

Step 4: Conclusion and Results

Some Cheap Alternatives
I wanted to go all out and get some real hydroponics equipment but it's not needed. My old system, as stated above, used tap water and just liquid fertilizer (~$3.50) as nutrients to grow an aloe vera plant and did fairly well. Instead of expanded clay, or any other hydroponics media, I just used some aquarium gravel I bought for a few bucks. Instead of buying a light, you can use the sun as long as there is a good location that receives a decent amount. You don't need to spend a lot of money to make your system work. Buying good equipment does provide benefits but it is definitely not needed for the amateur hydroponics enthusiast!

I decided to order some small herb plants online since starting them from seeds taking way too long and is often quite difficult. I got my plants in the mail and transplanted them. The cilantro started to droop and most of the plant died off... but! there was one little sprout in the middle that survived! In a few days it doubled in size and then I noticed more little sprouts starting to grow, so it's coming back to life! The parsley is doing well, a leaf or two started to die off, most likely due to the shock of transplanting them. I was a bit rough trying to get the dirt off the root. The majority of the plant, however, is deep green and looking good. The basil is pretty small but is responding to the light and directing its leaves toward it. The thyme is surviving. No real signs of it flourishing though. I also bought a few small spinach plants but I haven't had time to make more containers for them yet.

After I had transplanted my herb plants I noticed that the nutrient solution was not coming up the whole way in some of the pots. This was due to the fact that one pot had less solution than the others, allowing it to push all of its nutrients up into the plant and bubble, releasing the pressure needed for the other pots push the water up. In order to fix this, flood the system by turning the pump on. When one container starts to bubble, add more water/nutrient solution to it. When you add more, it takes more pressure to make it bubble and allows the other containers to fill up higher. It took me a bit of filling up but I eventually got it all evened out.

I hope this is all straightforward!!! Message me with any questions or comments, I love to help!!! Thanks for viewing!



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    98 Discussions


    Question 4 months ago

    What are you growing? I love this design and am building it for my agriscience class. Thanks!

    1 more answer

    I had some thyme, basil, parsley, cilantro, and spinach growing! Good luck with the build! Make sure all of your connections are air tight!

    i gbot a question here, what sort of aquarium pump do you need? a pump for air?or a pump for water?

    5 replies

    The idea is to pressurize tye resovore thus pushing the nutrient solution up into the plant.

    Very cool design. I am building a similar set-up for a science project, but I need to make sure that all plants are getting the same solution, so I will have one large chamber (a 3 liter bottle) with 9 hoses coming out it. Each hose will connect to a small planter. I have not built it yet, but I foresee a potential issue I wanted to know how you got around it. I need the solution to drain back into the main chamber each time the air pump turns off so it can mix with the other solutions. I worry that the air pump will maintain pressure in the bottle, not allowing the solution to drain efficiently. Did you have this issue? If so, how did you get around it? Also, when you have it up and running, how far up your planters did you have the solution rise? Thanks!

    3 replies

    How did it work out for you? Rather than nine hoses coming out of one resevoir, you can use one hose split into two using a three-way junction. Split that into two again, and those two into two again, and you have 8 equally-pressurised nutrient lines to feed into 8 or more planters.

    You may be able to use some T's from drip irrigation systems

    For the level of solution, I turned the pump on, then added solution until it topped off each plant.

    The way this design works, is that each plant has a sealed chamber with solution and two tubes. One for air, the other for solution/water. The solution/water tube goes straight up to the plant/gravel from the bottom of the chamber. The air tube blows air into the chamber, displacing the water, pushing it up through the solution/water tube, into the plant/gravel. When there is no solution left, the air goes though the tube, keeping all of the solution in the plant/gravel. When the pump turns off, the solution/water slowly drains back into the chamber since there is no air pressure keeping the solution/water in the plant/gravel.

    I do not know of a way to have one single chamber for the solution/water unless you have a massive container (like an air tight storage container) and each plant/gravel container is on top of it.

    Hope that helps.

    Brilliant system, very simply to design and build. I have created a similar, simpler system with good results after misunderstanding what you had written.

    The system I have made uses one large resevoir - in this case a standard 2l soft drinks bottle. The air is pumped into the resevoir at the top like normal, and nutrient exits via a tube as in the OP's instructions. The only real difference is that the tube splits into two via a three-way junction and then in to two again via two more three-way junctions before entering the planters which are also 2l soft drinks bottles. Thus the system is highly modular and expandable in powers of 2. I was initially worried that the pressure would not hold when the nutrient gets to the planters because at this point it is under 1/4 the pressure it was when it left the resevoir. But I guess the water behind it aint going anyway so the water in front has no place else to go and happily pools up into the planters. It is working fine for four planters and I would be prepared to believe that eight may work as well. I don't know what the limiting factor is, probably the size of the reservoir - but it seems even this tiny pump can handle air pressure equal to the weight of two litres of water. I'd also imagine the containers would not have to be at the same height, as long as the lengths of tubing on either side of the junctions are symmetrical.

    As with Dandeman's setup it is still quite hard to regulate bubbles in this setup and I'm not sure what the limitting factor is. When the reservoir is empty and the planters full the bubbles seem to pick a left/right direction at each junction fairly arbitrarily and I don't know if that depressurises that line or what - the other three planters stay full, and one bubbles away. Perodically the bubbling planter will change for some reason and another will start bubbling but not with any regularity or predictability.

    PROBLEM: The problem I am having at the moment is that even though I bought the cheapest pump I could reasonably find, it is too advanced for this project. It has a back-flow valve in it which prevents air (and hence water) from going back through the pump when the power is off - presumably to stop an aquarium from siphoning all its water onto the floor through the pump in the event of a power failure. Of course, that's not a problem for us - but the valve stops the planters from draining as the reservoir remains pressurised even when the power to the pump is off. What can be done about this problem?

    Someone on another forum (I think it was youtube?) said he solved this problem by using a needle to make a tiny hole in the air line. This slowed down the speed at which the planters filled, but increased the speed they drained. I don't want to do that, it seems like an inelegant and inefficient solution to me.

    In conclusion thanks for a great and helpful instructable. Any assistance that could be given regarding reservoir pressurisation would be appreciated!

    1 reply

    Great idea with the big reservoir! That way each plant will get the same amount of water as it floods. Only downside is you can't keep nutrients separate so if you're flowering tomatoes in one, you don't want to flower your basil in the other. Yeah, not sure what to do about that backflow. A pinhole may be the best way to solve that :/ Glad you got use out of the instructable! Thanks for the suggestions!

    Alternate solution.

    The problem you're having is due to the fact that the liquid in the system serves as the seal. If it starts to bubble, the seal is lost and the system depressurizes and the units downstream do not ebb and flow. This is only problematic because you're trying to pressurize the system in series.

    Instead of messing around with the solution levels in each unit, you could instead use an aquarium air distributor to pressurize each unit independently. (This also does away with the need to have both an input and an output on each container).

    For example, the distributor I'm going to link can independently pressurize 4 units without messing around with the water levels:

    The only caveat is - the amount of liquid in each reservoir will need to be equal., since they will all pressurize at the same time. If bubbling occurs in one before the others, it will still cause the system to depressurize. But I think what I've suggested here should simplify both the design and the effort to equalize the pressure across containers.

    4 replies

    Yeah getting rid of some of the seals would help out. And yeah, I did notice the balancing water problem. Gotta keep them all equal. I've abandoned this system and moving on to a larger setup.

    I figured you would - the obvious problem I see with this set up is how frequently you would have to replace the solution. As plants get bigger, they get hungrier. So it wouldn't be long before tending to this system could take quite a bit of work. ;)

    Exactly. This system was designed to be small and cheap. Not really too useful if you grow larger plants in it.

    Actually, they don't have to be equal, since each port on the distributor has an adjustment knob. So rather than adjusting the level of solution you can adjust the flow rate of the air going into the container instead (by twisting the knobs).

    This ability to adjust flow rate to each container could also let you use multiple size containers with the same pump. (Turn the flow rate up on a big container, and down on a small container until you the displacement rate works for all containers... just dial it in).

    how much does this project cost to make????????????