We’re back at Maker Faire 2019 with some improvements to our award-winning design. First, we wanted to modify the system so that it is easier to build. While the A-frame design (Maker Faire 2016/17) looks nice, some of the materials may be difficult to get and assembly is a bit tricky. Next, we wanted the design to be flexible enough for a variety of spaces - vertical, horizontal and different sizes. And lastly, we discovered that some physical locations don’t have easy access to electrical power. So, there is an option for a solar powered irrigation system.
PVC pipes generally come in 10 foot lengths. The ideal size of the pipe is 3” in diameter. There are different types of pipes. Drain pipe is the most common, least expensive, and readily available at Home Depot or Lowes. This pipe is ribbed and has a black interior. While this pipe should work fine, it is a bit flimsy and I don’t like the black interior. Instead I use 3" Schedule 20 PVC pipe. It is more rigid, but much lighter and less expensive than Schedule 40. Although Schedule 20 does not meet local plumbing code (thus not available at Home Depot/Lowes), it works great for hydroponics and can be found at irrigation supply companies. I get mine at Ewing Irrigation. Here is a good article about getting Schedule 20 pipe.
Most often the pipes have a flange at the end to connect pipes to each other. Cut off the flange section, then cut PVC pipes to desired length. Generally, I use either a 10” or 5’ section to maximize use of the pipe. Now, it is time to start cutting the holes in the pipes. Use a 2 ⅛” hole saw with the center spacing about 8” between holes. Also, for about 1/3 to 1/4 of the pipes, the holes can be cut at a higher density (3 to 4 inches between hole centers) for younger plants. Tips - when cutting holes, once the hole is started, reverse the direction in your drill to give a smoother cut. Also, an edge deburring tool greatly helps to clean the rough edges after cutting the hole.
One end of the pipe will be used as a drain. Drill an extra 2 ⅛” hole at the end of the pipe. Then drill a 1 ¼” drain hole inside that hole the goes through the bottom of the pipe. Insert a ¾" grommet in this hole. When installing the irrigation system, jiggle into place a ½” PVC pipe through the grommet for drainage.
Connect pipe end caps at the end of each pipe. Tip – instead of using PVC cement to hold the cap in place, try placing a plastic bag or two over the end of the pipe and then put on the cap. Not only will this provide a tighter fit, but the cap can also be easily removed to clean the pipe in the future. Lastly, trim the excess (and unsightly) plastic bag material.
3” PVC Schedule 20 pipe, 10’ section - Ewing Irrigation - $13.00 each
2 ⅛” hole saw - Home Depot - $10.00
¾" grommet - Amazon- $16.00 for 25-pack
3” End caps - Home Depot - $2.00 each (need 2 per pipe)
Debur Tool - Amazon - $14.00
The frame supports the pipes in a variety of desired configurations—horizontal (flat), or vertical, dependent on available space, and sun exposure. A “short” system will be about 5 feet long, while a full-sized system is about 10 feet long. You can also have as many or as few pipes as you like, within a few constraints. For vertical systems, each pipe should be about 15” between each level. You can also place pipes on both sides of the frame if it is in an open area, or one side if it is against a wall or fence. For horizontal systems, the pipes should be about 6” apart for full sized plants, 4” for younger plants.
The vertical system frame is fairly simple to build. Everything can be made from standard 2” x 4” and 1” x 4” wood. The end posts should be about 66” tall if you want 4 levels on one side, shorter if you want 2 or 3 levels. The 44” length supports a 5’ pipe.
2 end posts - 66” x 2” x 4"
2 span supports - 44” x 2” x 4"
2 leg supports - 28” x 2” x 4"
After these pieces are cut, assemble using 3 ½" lag bolts to connect the legs and posts. The span supports can be screwed in place. Also, in the top corners I use a metal tie connector or angle bracket to give added strength.
The next step is to make the pipe braces out of the 1” x 3” wood.
2 braces for each pipe,
4-7 pipes depending on configuration - 10” x 1” x 4"
After the wood is cut, take two boards and clamp them together. Use a 3” hole saw to cut a circle between the two pieces. Be sure to use a scrap piece of wood under the boards to protect your work surface. After the circle is cut through the boards, you will have two supports with a half circle out of each. Sand to smooth. Now mount the braces to the end posts starting at the top, then moving down 15” for each level.
The horizontal system frame works well when you have more space available. The concept here is to build a box out of 1” x 6” boards. The end pieces will have a cut out of half circles, using the same process describe above. The size of your box depends on how many pipes you want to hold, and the length of the pipes. In general, the 5’ long pipes work fine. If using 10’ pipes, another support piece will be required. Remember to leave about 6” between each pipe.
2 end pieces - 32” x 1” x 6"
2 side pieces - 44” x 1” x 6"
8 leg supports - 30” x 1” x 4"
After you cut the pieces of wood, take the two end pieces and clamp them together. Use a 3” hole saw to cut a circle between the two pieces. Remember to leave about 6” between each pipe and 4” at the end. Be sure to use a scrap piece of wood under the boards to protect your work surface. After the circles are cut through the boards, you will have two end pieces with a series of half circles out of each. Sand to smooth.
Take two of the leg supports and nail them together to form a right angle. Assemble the four legs and then mount the end and side pieces.
Each tube is filled with water enriched with minerals (more on that later) to keep the plants hydrated and fed. The water level in the pipes need to be high enough to touch the bottom of the plants held in 2” net cups. The height is controled by the height of the ½” PVC drainage pipe inserted into the ¾” grommet.
The bottoms of the drainage pipes need to be connected so that the water gets recycled to the water storage tanks. On a vertical system, the water drains to the next level down, and then finally back to the water tank. On horizontal systems, the drainage pipes are inter-connected to single pipe that goes back to the tank.
Tanks specifically designed and sold for hydroponics can be quite expensive. Try using the heavy duty storage bin (about 27 gallons, black with yellow lid) that are available at Costco or Home Depot. These 27 gallon system are sufficient for a 5’ system to operate for 5-7 days, or more. If more water storage is desired to give a larger margin of safety in case of leaks, you can connect two or more tanks togther using Uni-seal grommets and ¾” PVC pipe.
The water pump is a critical component to make the hydroponic system work reliably. Typically you will use a pump designed for a water fountain. Hydroponic systems typically don’t need a high volume of flow, so don’t get one that bigger than required. The critical specification is the water lift - particularly if using a vertical frame. Get a pumps with specifications similar to this pump. See the section below if your system is not near AC power.
For a vertical system, only a single feed line is required as the water flows from the top pipe to the bottom pipe. The feed line is a standard ¼” drip line hose The trick is to connect that hose to the pump. Here are the part to make this fixture.
• ½" slip x NPT Male (threaded connect from pump to ½" PVC pipe)
• Very short piece of ½” PVC pipe
• ½” slip X ¾” slip
• Very short piece of ¾ PVC pipe
• ¾” PVC end cap
• ½” top hat grommet (fits ¼” drip line hose)
Drill a ½” hole in the ¾” PVC pipe. That should be large enough to fit in the top hat grommet. Then insert the ¼” drip line. Use a piece long enough to reachthe top pipe. Drill a ⅜” hole in the pipe to hold the hose in place.
For a horizontal system, a feed line is required for each pipe since there is a drain at the end of each pipe. Instead of a single grommet in the ¾” pipe, there needs to be one for each pipe. Generally, this piece is called a “manifold". The manifold can be close to the pump as in example above, but then there are multiple hoses that can look a bit messy. Instead, use longer pieces of PVC pipe from the pump and locate the manifold closer to pipes.
Plants grown in the ground absorb minerial nutrients that are dissolved in soil as they are watered. The magic behind hydroponics is that the “food” or minerals are directly in the water. But the big question is how much nutrients should be in the water. The pH level, which affects how much of the nutrients a plant can absorb, is also very important.
Fortunately, the nutrient and pH level can be easily measure with relatively low-cost meters. The pH level is rather straightforward as there are lots low cost meters to measure pH. For nutrients, as you add more minerals to water the electrical conductivity - or EC - changes. Some of these hand held meters are very low cost - sub-$20 for both meters. But a good meter (about $200) is well worth the cost to be confident in your pH and EC level. This is the meter I use.
To adjust the pH level of your water, generally you will need to lower the level by adding acid to the water. The ideal pH for green leafy vegetables is 6.0.
Hydroponic nutrients come in a two-part mix - aptly name Part A and Part B. At high concentrations, the mineral bond with each other and need to be in separate solutions. Once they are added to water, they are fine in the diluted form. Be cautious as there are many very expensive 2-part hydroponic liquid nutrients - target another cash crop. Unforunatley purchasing a dry mix for these nutrients in small quanities is a challenge. I get my nutrients for $70 at AmHydro.com and that is enough for 5 gallons of Part A and Part B. That will last a very long time for a home system. If I find a better solution for smaller batches, I’ll update this section.
Electrical power is not always available or convenient to the location of the hydroponic system. Initially we believed that water needed to be flowing 100% of the time, so it would not be feasible to have a large solar panel, battery, and AC converter to run a pump 24/7. Then, we had a hypothesis: since the pipes were always filled with water, the water did not have to flow 100% of the time for the plants to grow. We ran some tests and found that the leafy greens grew just fine with intermittant flows of water.
Next, we converted the system to 12 volt DC power to avoid the inefficiency of an AC converter. It was easy to find 12 volt water pumps (think marine bilge or fountain pumps), but the power system needed to be balanced between the power produced by the solar panel, stored in a battery, and consumed by the pumps over an average 24 hour period of sunlight and darkness. To achieve this goal, a timer and speed controller were added to conserve total power consumed. These made a huge difference. We also found a specific solar controller that displays both powered produced by the solar panel and consumed by the pump to help us “tune” the system.
If you want to add solar power to your hydroponic system, you can do this for approximately $225 using parts that can be found on Amazon. Below is a list of parts I used - feel free to try different parts from other sources. These are just ones that I found that worked. Refer to the wiring diagram to hook up the various components.
Parts from Amazon
Solar panel - 50W 12V solar panel - $69.99
Battery- 12 volt, 18 amp hour Lead Acid - $39.20
Solar Controller - GHB 20A 12V 24V Solar Charge Controller - $38.99
Timer - 12 volt timer relay - $11.99
Enclosure - Altelix NEMA 17x14x6 - $59.99
Pump - 12 volt pump - $10.99 - $14.98
Look back at our display at earlier Maker Faires