Hi everybody! Long-time listener, first-time caller. =D
I work for a Biosystems Engineering department at a university and after a few years of being exposed to controlled environment agriculture I decided to try it out as a hobby. I am interested in urban sustainability and with food security a very real threat (see: the 2050 problem) I envision a future where average citizens will depend on informal networks and growing their own food to fulfill a portion of their daily diet. To that end, I aim to create simple systems that don't take up much space and are relatively inexpensive.
This display was my second design and the most aesthetically pleasing, at least to me. Dimensions are 24"x36"x22" and requires about 3 gallons of water that I have to top off once a week or so. Otherwise this thing requires very little maintenance.
Step 1: Materials and Setup
I bought all of this stuff, except the lighting, at Home Depot. I knew exactly what I wanted to do and the assembly is very simple, so it only took me about 2 hours start to finish.
- Set of hole saws, I borrowed from a friend.
- Drill bits, 1/2" and 1/4"
- PVC pipe cutters or a hacksaw.
- Proper Ventilation! PVC cement is strong stuff, read the directions for safe use.
- 28qt Latch Box/Tote, $6.98
- 20' of 1.5" diameter PVC, although I only used 12' for this build. Roughly $10 for a 10' length.
- Two 1.5" PVC caps ~$1ea
- Ten 1.5" PVC 90 degree elbows, ~$0.40ea
- PVC Primer and Cement, packed together, $8
- 70gph fountain pump, $20. This is probably overkill and you can get one that pumps less, so long as it has an effective pump height of 2.5ft.
- 1/2" irrigation tubing. You only need a few feet, but I ended up getting the 100ft coil from HoDe for $10. Useful stuff to have around and I've used it a lot for other builds.
- 1/2" 90deg compression elbow, $1
- 1/2" barbed in-line shut-off valve, $3
Optional Lighting Rig (see last section): $30
Project total: ~$75-105
Step 2: Design and Build Frame
I went with a relatively simple NFT design (nutrient film technique) where a thin layer of water is pumped to the top of the system and travels back to the water tank via gravity. The whole thing is inspired by classic A-frame designs and I thought I'd maximize space by creating a pyramid, but in reality this probably is not the case... IDK. However, the height of the design definitely helps the water flow versus other hydroponic setups where the pipes are laid flat and parallel to each other, and it definitely looks cool.
First, layout your design on paper to figure out the dimensions, lengths of PVC required, and number of joints requiring an elbow (my image is obviously not to scale, lol). I don't quite recall how I arrived at these numbers, so you're free to copy my measurements or, *shudder*, do some math.
Next, cut your lengths and lay them out on a flat surface to ensure it all fits together and the 'layers' fit within one another.
Third, using a 1" hole saw, cut as many evenly-spaced holes in your lengths. The spaces should be at least 4-5 inches apart so your plants have room to grow on either side.
You will probably notice that I stupidly did not cut my holes before gluing it together, which made cutting the holes rather difficult. TIP: it is best to use a bench vise when cutting holes in tubing of any kind! Work smarter, not harder.
Fourth, take one of the PVC end caps and cut a 1/2" hole in it with hole saw or large drill bit. This end cap goes at the top of the frame and is the water inlet. Don't make the hole too wide, you want a tight fit.
The final step is to prime and cement it all together. Add a thin layer of primer to the each surface of the connection, i.e. the exterior ends of the pipes and the interior of the elbows. Let the primer dry and repeat process with the cement. The cement dries quickly, so pace yourself with one connection at a time. Work from the bottom up! I used my trusty and versatile speed square to ensure the height and angles were consistent, but it really does not matter so long as you maintain a subtle-ish slope. Again, be sure to read the directions and use the cement and primer in a well ventilated area. Don't blame me if you didn't read this first and pass out. =p
Step 3: Prepare Plumbing and Assemble
There isn't much to preparing the water tank beyond cutting some holes in the top. My final design requires a 2-3 inch hole in the center to act as a drain, a 1.5" hole for the pump outlet, and another hole for the pump's power cable to slip out.
To set up the plumbing:
- Put the pump in the tank
- Put the lid on
- Set the frame on top
- Measure and cut a length of the 1/2" irrigation tubing from the top of the pump, through the hole, to 3-4 inches above the top of the frame. Be sure the pump is touching the bottom of the tank.
- Cut this length in half and use the in-line valve to rejoin the two pieces.
- Use the compression elbow at the top to cut and re-angle your tube into the frame's inlet. Without the elbow the tube will likely pinch.
- It is best to have about 2" of tubing inserted into the end cap to best prevent back flow leakage.
The in-line valve is used to finely control the water flowing into the system. The water should trickle and flow, but not gush!
- You will notice in some of my pictures that the "alpha" version of this build drained at the end by a tube inserted into the side of the tank, this proved to be annoying for several reasons and was ultimately ugly. In the end, I opted to drill 1/4" holes on the inside of the final leg and inserted some zip ties to act as wicks. Drains beautifully now.
- The brick is there to put weight on the center and draw the water toward the drain. I replaced this with some nice looking stones from the garden in the final version.
- Also, full disclosure: I cut the pump outlet in the lid in the wrong spot and, rather than cutting again, I stubbornly added another couple of elbows for a weird zigzag.
- Don't repeat my mistakes: Measure thrice, cut once. xD
Step 4: Placement and (optional) Lighting
Add water and plants
Once you have it all put together, you just need to add water and plug in the pump. I only fill the tank to the inner lip, around 3 gallons, enough to keep the pump submerged. The PVC cement is watertight and if used correctly should not leak, but should any appear you can seal them with a bit of the cement on the outside. Just don't over do it.
If there are no leaks, start adding plants. Mature plants with a root system can just be plugged in. If store bought, you need to clean as much soil from the root ball as possible before you install the plant. If you want to start seedlings, I've found that the best method is to use cheesecloth to create a little nest for it. I do not recommend using rockwool because it breaks down too quickly and dirties up the system. You can also fill the tube with clay pellets, which works OK, but is also a real pain to keep clean.
The ideal place is a room with a lot of light or near a window, but this depends on the type of plants you intend to grow. It only weighs about 25-30 lbs with water and plants in it, so it is no big task to move around as needed. If you don't have good lighting, I highly recommend purchasing a 24w LED grow bulb (http://a.co/6II0NKU), clamp-style fixture (http://a.co/7BufCCy), and a plug-in timer (http://a.co/janfpSr).
Those items are currently less than $10 each on amazon, bringing the project total up to ~$105 with plenty of spare parts to build a smaller system that only needs a pump and a few other things. You don't need a lighting system, but the plants sure like it.
If you want to save money, just buy the bulb and put it in an existing fixture above your system. The ceiling fan above my dining room table was an interesting choice. In the end, I moved this into my kitchen and got a fixture with a timer that runs while the family is sleeping so it doesn't bother the eyes.
It's probably not a good idea to stare directly at these bulbs too long, but I'm not a doctor. ¯\_(ツ)_/¯
I realize I said above that I was interested in developing these systems for the purposes of food production, but as this system was a proof-of-concept I decided to go with some hardy ornamental plants as my pilot group, which have since proven hard to remove. I intend to build another using this design and pilot some butter head lettuce, which grows very well in A-frame NFT systems like this one.
I keep feeder fish in the bottom and feed them through the drain hole on the top. These guys help provide food for the plants and the plants help keep the water clean in return. Whether you decide to go hydro- or full aquaponic, you're going to need to occasionally blast your system with some Zym Bac natural beneficial bacteria (https://www.amazon.com/GROWN-PONICS-Natural-Beneficial-Bacteria/dp/B00FG2KH00/). It is probably not the most balanced system, but it seems to be viable and sustainable.
That's all, hit me with them comments.