The Hydrofarm was an extension of a previous proof-of-concept for an automated greenhouse. We were tasked to build a larger version that could be used in a biology classroom for experimentation. This placed several limitations (like being able to fit through doors) that became the reasons behind many of our design choices. The Hydrofarm is a vertical hydroponics farm, designed to be compact as well as allowing for experimentation and data collection. To this end, it has two separate sections (with separate water sources and growth media) to grow plants, which allows for the possibility of comparing two variables, such as water from different rivers, or a control and an experimental group. Each section has the water trickle down through several pipes containing growth medium and plants, and eventually recycles the water back into the storage tank. Additionally, it has a sophisticated sensor suite that can measure salinity, water turbidity, temperature, and pH. This data can either be displayed on a laptop in real-time or accessed from an SD card for later analysis. If necessary, the farm can even detect water leaks, and sound a small alarm to alert the user of the problem. For our purposes, we tested it by running an experiment on how different lighting would affect plant growth. One section of plants was grown with regular lamps in a consistent day-night cycle, while the other section of plants was grown using colored LED lights. The water conditions were measured daily to verify that the two sections matched.
With all the materials gathered, it’s time to begin by cutting all of the PVC pipes to the correct lengths. You can vary these for your own model of course if you want, provided they still make a closed loop. But for the sake of this I will use our measurements.
Once you’ve cut all of the pipes to size, the first step is cutting the slots in the large PVC Pipes in which you will insert the plants. To make these slots, take the 4” Outer Diameter 40” long PVC pipe and cut approximately 1.5” wide and 35” long slots in each of them.
Now that you (presumably) successfully have slots in each of these, you need to put the transitions of each end of these large pipes. To attach the 4” OD (Outer Diameter) to 2” OD transition, you’ll want to first prime (with primer) the outside of the 4” pipe and the inside of the transition. Once the primer has dried and set, you’ll need to use a strong adhesive, such as Plumber’s Cement to attach the transitions to each end of the pipe. Make sure to put them together quickly and carefully after the application of the cement because it sets very fast and is hard to undo. You’ll also need to put one of these transitions on one end of each of the 20” long 4” OD pipes.
The next step is to insert the valve connectors into all of the transitions you just put on the 4” pipes. Do this using the same method you used to attach the transition using the primer and cement. This will be the attachment method for all other PVC pipes.
Next you’ll need to make holes in the table piece for the pipes to fit through. This is easiest done by placing the tubes on top of the table with adequate spacing in between and marking the place on the table, then cutting it with a hole saw. Only the 1” piece needs to fit through the table, so the hole should be about that big. Once the hole is made, place the pipes into these holes.