The TechnoArugula project is a small high pressure aeroponics project built around a simple Arduino micro controller board controlling a high pressure aeroponics pump system. The objective of this project is to demonstrate the feasability of growing fresh salad greens in a DIY, controlled environment.
The first harvest of Arugula took about 4 weeks to grow. The arugula was grown under 40 watt PAR LED lights for 16 hour days with a high pressure aeroponic nutrient solution being applied for 1 second every five minutes. If you do the math the first harvest used 0.64 killowatt hours a day for 30 days totaling 19.2 killowatt hours. At seven cents a killowatt hour the cost of electricity for the first harvest is about $1.35.
Each harvest is about the same volume as one of the smaller tubs of greens you can buy at the store for three or four dollars. Each subsequent harvest takes about a week to grow for a total of about 35 cents. Pretty good deal.
| Variable | Value | Units | Notes |
|---|---|---|---|
| Flora Micro | 60 | ml | |
| Flora Grow | 60 | ml | |
| Flora Bloom | 30 | ml | Using the proportions for vegitative growth not bloom |
| concentration | 922 | ppm | This is a little low. I'll go 90, 90, 45 next time |
| pH | 5.67 | ph | This is on the low side but ok |
| Variable | Value | Units | Notes |
|---|---|---|---|
| PAR | 375 | µm/s/m2 | micro moles per second per square meter |
| duration | 16 | hours | I'm running lights only when rates are cheap |
| DLI | 21 | m/d/m2 | moles per day per square meter |
Fifth harvest of Arugula
- high pressure pump
- high pressure accumulator
- filter cannister
- misting nozzles
- high pressure tubing
- high pressure fittings
- high pressure solenoid valves
- grow lights
- plant support trays
- 1/2" PVC Pipe
- 1/2" PVC Pipe Fittings
- Pond liner
- Plastic 2' x 4' x 6' shelving unit from Home Depot
The system is organized around a plastic shelving unit with about 20" between shelves. Lights are attached to the underside of a shelf and the plants are below the lights on a plastic lined box sitting on the next shelf down. The spray system is a set of 18 cheap misting nozzles connected by 1/4" high pressure tubing.
TechnoArugula is a simple Arduino ini file that makes use of a relatively simple state machine to allow asynchronous execution of on/off for each valve and for testing and controlling temperature and CO2 levels. Basically each state is represented by a task function such as timerTask1StartFunction or timerTask1EndFunction. Each state function checks to see if it's current state should end by checking "millis()" against an end time. When the state has expired it executes it's task (eg turning a valve on or off), sets the next state function and the next end time for that state and returns. For example, timerTask1StartFunction waits for it timer to end and then turns on it's valve, sets the end time to the current time plus a half second and sets the state to timerTask1EndFunction. The current state function is executed in the loop along with other tasks and because none of the state functions ever calls delay() other tasks can execute while something like a valve is on.
- Making better root chambers
- Adding CO2 enrichment
- Adding cooling
- Adding external control of spray timing, cooling and CO2 enrichment.
- Use arduino to sense pressure to turn pump on and off