Introduction: Small NFT Hydroponics System
Hydroponics is a type of agriculture that uses no dirt, and usually results in larger, fuller plants. I recently became interested in the topic, and decided to start my own vegetable garden using the Nutrient Film Technique (NFT). It involves a channel of nutrient enriched water constantly flowing past a plant's roots. The system that I'm demonstrating here is just one example of infinitely many possibilities. Take my work and use it as inspiration for developing a system that suits you and your needs.
Step 1: The Idea
Because hydroponics requires a resevoir for water to be drawn from and returned to simultaneously, and I was just building a small system, my design has two gullies. This allows the water to easily go full circle.
Along with the water pump, my system uses gravity to assist the flow of water. Each end of the PVC is one inch higher than the end that comes next in the circle. The end of the tube that water enters from is the highest, and the end that it leaves from is the lowest. To achieve this, I built supports out of lumber for the pipes. The supports also keep them high enough to be above the reservoir, so that gravity will return the water to it.
Step 2: Materials
- 66" of 4" PVC Pipe - If I didn't already have PVC, I would have probably bought plastic gutters.
- Assorted lumber - Go to the cull wood section of your hardware store. This is the wood they cut for other people who didn't want the scraps. I got four 43" 2x4"s, one 1.5x7.5x58" piece, and a scrap of plywood for $3.
- Screws and such
- 4 rubber adjustable end caps with hose clamps - about $3 each
- Submersible pump - I'm using this
- Teflon tape
- 16 oz Plastic cups
- Irrigation tubing
- Opaque Bucket
- Plumbing cement
- Growing medium - I used expanded clay ball
- Hydroponics Nutrient
Step 3: Build the Stands
Once you figure out the height of your reservoir, you can start designing your stands. Mine is about 13" tall, so my stands are 13", 14", 15", and 16". After cutting the lengths, I cut a triangle (with a height of 2.5") out of each one to hold the PVC.
I'll assume you've already cut the PVC in half...it doesn't really deserve it's own step.
Next, I attached them together with the 2x4's. I found out the hard way that it's easier to make them level if you attach the 2x4's mid way up, instead of at the bottom.
Step 4: Plumbing
You'll need to drill a hole with a spade bit suitable for your tubing in each of the end caps. Drill the holes at the height that you want your water level to be at. I didn't think about it at first, so you'll see in the pictures that they're at the edge, I later had to adjust this, but there's a picture of that, too. Make sure your water level is high enough that the bottom of your cups will be submerged.
My pump came with a removable attachment for the tubing, so I wrapped one side of it with Teflon tape and used plumbing cement to attach it to a piece of tubing long enough to reach from the upper tube to the bottom of the reservoir. I then pushed the tube through an end cap's hole. Push another piece long enough to reach from the lower tube to the reservoir. Then attach two end caps via tubing long enough to fit on both pieces of PVC.
When I tested the system like this, it ran surprisingly well, with a just a few small leaks. Use the plumbing cement to seal around the outside of all the tubes. Plumbing cement isn't the most safe substance (toxicity wise), and even though it's probably OK, by just sealing the outside, it at least makes me feel better about. Luckily this stuff cures in two hours, so you can do another test run pretty quickly.
A lot of people recommend cleaning everything with a heavily diluted bleach solution to help ward off algae. I did this before I had drilled any holes. It was easy to fill the pipes and then shake them with the end caps on.
Step 5: Holes
Depending on your plants, the spacing of your holes will be different. I wanted to plant at least six plants, so my spacing worked out to be 8-9 inches between each hole. I would have spread them out farther if I could, but my PVC isn't long enough.
We have an adjustable door knob drill bit that drills holes up to 3" wide, so I cut a skewer to 3" and found where on my plastic cups they have that diameter. Hold it up to the PVC and see if it's deep enough. It was. Unfortunately, the only drill we have with a chuck that could fit that bit was a hand drill. At first I tried the "drill a whole every millimeter and cut it out" method...but I didn't have the patience. Instead, I used a 2.5" drill bit and sanded the rest down with my Dremel. If you have to use a Dremel on plastic, make sure to wear a mask in a well ventilated area and clean up all the dust afterward.
Rinse the dust off of the pipes.
Step 6: Assemble
Bring everything out to your final destination and set it up. Because mine is up against the screen of our porch, the lower side faces out, so everyone can get equal amounts of sunlight. Double check that the stands are all in the right orientation...i spent about 20 minutes trying to figure out why the water wouldn't run correctly.
I drilled three holes in the lid to my bucket, one for the intake tube, one for the output tube, and one for the power cord. It allows me to leave the lid on, and thus help prevent algae from growing.
Step 7: Cups
Drill plenty of holes in the bottom and edges of each plastic cup, for the roots.
Use the cups to measure out clay balls into a bucket of water. The water will wash off any dust that has accumulated on them.
Step 8: Planting
Carefully use a hose (I like the flat setting) to clean as much dirt as possible off the roots. Try not to mess them up...they don't like that so much. Once they're clean, surround them in the cups with clay balls. Use enough that they can support themselves and stand tall.
When you're arranging the plants in the system, keep in mind what kind of plant they are. Put taller plants in the back, so they don't block the sun. My plants that grow heavier veggies are on the lower section, so that I can build a table from the plywood and 2x4's to support their crops.
Step 9: Nutrients
- Nutrient solutions come in all sorts of varieties. I bought a general purpose "grow" solution that also has a "bloom" counterpart for when the plant begins to...bloom.
Step 10: Maitenance
The nutrients have to be changed periodically, and it's hard to tell when it needs to be done. People do it anywhere from once a week to once a month, and it depends on how much you mix at a time.
Hydroponics.net recommends that you add fresh water as it's used by plants, because even though water is absorbed, nutrients still remain, and can get more concentrated. They said that once you've added half the amount that was originally in there, it's time to change. So with my 7L, once i've had to add 3.5L of additional fresh water, the nutrients will be mostly depleted.
Some people also monitor their ph levels. Pool stores generally will check it for free. I don't have a lot of information on the subject to offer, however.
Other than that, there isn't a lot that you have to do except care for the plants as you usually would.
Step 11: Resources
- Instructables has a lot of great information on hydroponics
- hydroponics.net has a good FAQ
- SimplyHydro.com has a good explanation of some types of hydroponics