Automated Aquaponics System



Introduction

This project is the realization of an autonomous aquaponics environment I worked on with Ethan Michalak and Damien Stoffel. We chose to develop this as our project for our Engineering Design & Development class. Over the course of nine months, our team designed, prototyped, and fabricated a portable, fully-automated aquaponics system for use in research and academic instruction. At the end of the year, we donated the system to the biology and environmental sciences classes at our school, where it is being used to help students with research projects and other demonstrations.


System Overview


Aquaponics is a farming technique which combines both aquaculture and hydroponics subsystems into a single cooperative environment. Our system utilizes a fully autonomous aquaponics systems which records temperature and pH readings from the system for use in research and practical demonstrations. Water is cycled throughout the auqaponics from the aquaculture tank into the hydroponic tubes, which help to filter the water, which is then pumped back into the tank at the bottom. This process repeats cylically allowing for a symbiotic relationship between the fish in the tank and the plants being grown above them.


For this project, minnows were chosen to be used in the aquaculture portion of the system. The minnows were fed daily by an off-the-shelf automatic fish-feeder, eliminating the need for manual human feeding.


In the upper, hydroponic section of the system, plants are grown in three enclosed channels, each with four openings filled by one of the NFT Units. The NFT Units contain the plants (in this case, raddish sprouts were grown) and allow for passive watering of the plants as water flows through the channels. Above the channels, a combination UV/IR/Red/Blue growlight is held to act as an artificial light source.


The units for holding the plants were developed based around the Nutrient Film Technique (NFT). This allows for very efficient, purely hydroponic feeding of the plants through their roots. The roots grow through the lattice structure in each cell and secure themselves to the base as they leach nutrients from the water while still mostly exposed to the surrounding air.


The whole system was controlled by the combined use of a Programmable Logic Controller (PLC) and a Raspberry Pi. The PLC was used to control essential tasks that needed to be more rugged and run without interruption for long periods of time, without worrying about software updates or data transfers. The Raspberry Pi was used to control all forms of data collection and analysis from the temperature sensors and the pH sensors. This system was built in a modular fashion to allow the addition of more complex sensors in future research.



Electronics and Software

The whole system is accessible through a web interface running on the Raspberry Pi written in Flask. This interface is visible when connected to the network broadcasted by the Pi. The webserver periodically queries the two DS18B20 thermometers and the EZO pH Sensor, and displays the information for the end user to see. This data is also recorded in a .csv file which is stored on the Pi, and can be downloaded from the webserver for future reference and analysis.



The two water pumps are controlled by the PLC. This ensures that no matter what happens to the Raspberry Pi, the water continues cycling throughout the system.



Power to the system in supplied through an normal AC outlet. The AC power is directly supplied to the growlight, and converted to 12V DC power to control the PLC and the water pumps. 12V DC power is too much for the Raspberry Pi or its sensors to handle, so the voltage is stepped down through the use of a LM7805 chip. The Raspberry Pi can optionally be powered over USB as well.

Fabrication

Below is a chronological collection of images from our fabrication process. Click on any image to learn more.

A plastic cart was bought for portability, modularity, and to make the overall build process faster.
4" PVC pipe was used to make the channels. The three channels were built to fit the top of the cart.
Four 3.5" holes were cut in each channel using a hole saw.
Wooden stands were used to suspend the growlight.
A thermometer is embedded into the hydroponic system to measure temperature at predetermined intervals.
The control panel was 3D printed to house the Raspberry Pi, PLC, and power adapter.
Connected directly to the Raspberry Pi is two thermometers and a temperature sensor. The sensor mount is modular and made to be replaced easily on the control panel.
The initial prototype for the NFT units was successful, with the roots growing into and through the lattice structure. Black ABS was later swapped for white ASA to prevent the plant from heating up and to prevent degredation ABS experiences from the UV light.
To save time while the full aquaoponics system was being constructed, plants began growing in a miniature hydroponics settings inside the NFT units.
The control panel fully connected.
The final system, with all parts assembled.
The functional prototype.

Acknowledgments

We'd like to extend a special thanks to the following people for helping us out immensely with this project:

- Kristine Jennings, for use of her classroom and her expert knowledge of aquaponics and biology.
- Robert Michalak, for his extensive knowledge of electronics and fantastic encouragement.
- Michael Martin, for everything.