5 Gallon DWC Bucket

The benefits of deep water culture comes from the simple design with few moving parts – a bucket and an air stone are the only real requirements. This simplicity makes it a very accessible growing technique for beginners or budget growers. Additionally, the high levels of oxygen exposure experienced by the roots encourages robust plant growth and provides optimal growing conditions for many types of plants – especially fruiting plants such as tomatoes and peppers. This type of system is also very fault-tolerant, since a power outage or equipment failure won’t prevent plants from receiving the water they need.

Deep Water Culture system using Hydrobot

HydroBot modules can be used to monitor and control a deep water culture hydroponic system:

• AirSense monitors air temperature, humidity, and pressure, and ambient light level, to track changes in the environmental growing conditions.
• RelayDrive controls lights, bubblers, fans, and heaters to regulate growing cycles.
• WaterSense monitors water level and temperature to maintain the water reservoir.
• The Master Control computer manages communication, scheduling, and logging to the database.

DWC style hydroponic growing is a simple, low-cost way to grow a wide variety of plants. No matter what type of plant you grow, HydroBot’s modular and flexible design can be easily adapted and scaled to meet your needs.

HydroBot is an open-source hardware and software project. All source can be found in the HydroBot repository, and more posts about the project can be found here on the Protofusion Blog.

Original artwork by Kayla Curtis.

NFT Hydroponic System

NFT systems typically consist of plant-filled channels and a water reservoir with a re-circulation pump. The pump caries water from the reservoir up to the top of the channels, where it runs down past the plant roots and drains back into the reservoir. An artificial light is required if adequate sunlight is not available, and air movement from wind or a fan keeps the plants stimulated. Aeration is also important to keep up the dissolved oxygen content of the water, and can be provided by an air stone and bubbler.

NFT system using Hydrobot

HydroBot modules can be used to monitor and control an NFT hydroponic system:

HydroBot RelayDrive module installed in an NFT hydroponic system

• AirSense monitors air temperature, humidity, and pressure, and ambient light level, to track changes in the environmental growing conditions.
• RelayDrive monitors water flow rate and controls the light, pump, bubbler, fan, heater, and fill and drain solenoids to regulate growing cycles.
• WaterSense monitors water level and temperature to maintain the water reservoir.
• The Master Control computer manages communication, scheduling, and logging to the database.

NFT style hydroponic growing is very effective at producing leafy plants and can easily be scaled down to a small herb garden or up to a large commercial crop of lettuce. No matter what size garden you have, HydroBot’s modular and flexible design can be easily adapted and scaled to meet your needs.

HydroBot is an open-source hardware and software project. All source can be found in the HydroBot repository, and more posts about the project can be found here on the Protofusion Blog.

Original artwork by Kayla Curtis.

Hydroponics is a method of growing plants without soil, using mineral nutrient solutions dissolved in water. Plants use light to turn water and carbon dioxide into the food they need, through a process called photosynthesis. As long as the plants have enough access to water, air, and nutrients, dirt is not necessary for plants to grow.

Image: Wikimedia Commons

The word hydroponics comes from two Greek words, “hydro” meaning water and “ponics” meaning labor. The concept of soil-less gardening or hydroponics has been around for thousands of years — the Hanging Gardens of Babylon and The Floating Gardens of China are two of the earliest examples of hydroponics. Modern hydroponic systems are based on the same principles as their early predecessors and have been developed extensively in recent years to improve both yield and efficiency, leading many to believe that hydroponics will play an integral role in feeding future generations.

Types of Hydroponic Systems

Hydroponic systems can take many forms, each with advantages and disadvantages, but all with the common goal of delivering water to plant roots. Some systems are geared towards specific types of plants, while others are designed with low cost, large crops, or easy maintenance in mind. These are a few examples of a variety of commonly used hydroponic system designs.

Continuous Flow/NFT

Image: Protofusion

Nutrient Film Technique (NFT) recirculates a shallow stream of water containing nutrients past the bare roots of plants in a channel, covering the roots with a thin film of nutrient water. This keeps the roots moist, while still exposed to air, which provides access to plenty of oxygen.

Deep Water Culture

Image: Atlas Hydroponics

Deep Water Culture suspends the plant roots in a solution of nutrient-rich, oxygenated water. As the roots grow, the water level can be lowered, exposing some of the roots to air, which increases access to oxygen.

Aeroponics

Image: Farming 4 Change

Aeroponics uses a fine mist of nutrient water to deliver nutrients to the plant roots. Suspending the roots in a mist-filled enclosure gives them simultaneous access to both nutrients and oxygen from the air. To optimize nutrient delivery without blocking oxygen access, the water micro-droplets must be smaller than 50 microns.

Ebb and Flow

Image: Active Aqua

Ebb and Flow (or Flood and Drain) systems flood the roots of plants in a growing medium with nutrient water for a short period of time (5-10 minutes) before draining back into a reservoir. This gives the roots the water and nutrients they need, while exposing them to air for the rest of the cycle.

Rotary

Image: Omega Garden

Rotary systems use a continually rotating circular frame with plants lining the inside and a light source at the center. Rotations take place as often as once an hour, and the plants receive nutrients once per cycle. Due to their constant struggle against gravity, plants typically mature quicker than more traditional methods.

Aquaponics

Image: Back to the Roots

Aquaponics is a symbiotic growing technique that combines plants and fish in the same system. Ammonia and other by-products released by the fish are broken down by bacteria into nitrates and nitrites, which are then used by the plants as nutrients.

ProtoModule Features:

• STM32F0 microcontroller
• 11 GPIO Pins
• 0.1″ Pin Header Breakout
• 3 LEDs to indicate device status
• 6-30V input works with 12V and 24V systems
• JST-PA series connectors
• Parallel bus connections for daisy-chaining
• Protofusion pogo programming interface
• Open source design

Since it is intended to be used as a development board, this module has no predefined behavior. The 11 GPIO pins were selected to provide a broad range of functionality and can be used as analog, digital, or frequency inputs, digital, or pwm outputs, SPI, I2C, or UART communication ports, timer/counter channels, and more. This flexibility enables interfacing with a variety of sensors and actuators, which will be useful in testing out new HydroBot features before integrating them into dedicated modules.

All source can be found in the HydroBot repository, including firmware source code and hardware files. The BOM and generated gerber files are also included for easy replication.

HydroHub Features:

• 8 channels for connecting HydroBot modules
• 5.5mm DC barrel jack for power input
• 6-30V input works with 12V and 24V systems
• Selectable 120Ω CAN bus termination resistor
• Power indication LED
• JST-PA series connectors
• Open source design

JST-PA Series Connectors

This design introduces the switch to JST-PA series connectors for HydroBot modules. These connectors, although somewhat bigger and more expensive than the JST-ZH connectors used previously, will allow for lower gauge wiring and much higher currents than before. The new connectors support 22-28 gauge wiring and up to 3A per pin. All new module designs going forward will use JST-PA connectors and existing modules will be updated as part of the next revision cycle. The first module that has been updated to include the new connectors is the AirSense module, which has also added a light sensing feature. Other HydroHub features to note include a constant current driver for the power indication LED to keep brightness consistent over the entire input voltage range, and a CAN bus termination resistor that can be selected using a simple jumper to accommodate the needs of various network topologies.

All source can be found in the HydroBot repository. The BOM and generated gerber files are also included for easy replication.

RelayDrive is a HydroBot module designed to drive relays and other electro-mechanical devices. It consists of 4 low-side outputs, each rated for 1A continuous current, as well as 4 digital inputs, and is controlled over CAN. This module is intended to drive mechanical relays, solid state relays, and solenoids for controlling devices such as lights, pumps, heaters, fans, and valves in a HydroBot hydroponic system. 

RelayDrive Features:

• STM32F0 microcontroller
• 4 low-side 1A outputs
• 4 opto-isolated digital inputs
• 3 LEDs to indicate device status
• 6-30V input works with 12V and 24V systems
• JST-ZH series connectors
• Parallel bus connections for daisy-chaining
• Protofusion pogo programming interface
• Open source design

Each of the outputs of the RelayDrive module can be controlled as discrete on/off switches, or can be configured as PWM outputs. Each of the inputs can also be independently configured as digital inputs or frequency inputs. Frequency inputs are measured in Hz and can currently read input signals up to 1KHz. The default firmware uses a CAN baud rate of 500K. It sends out status messages on ID 0x204, with digital or frequency input readings, and receives command messages on 0x203 to control outputs and set input and output configuration.

Because many devices in a hydroponic system run on mains power and require relays for control, I packaged up 4 solid state relays in a 2 gang electrical box. This keeps all the relays together without exposing any hot wires, and the 4 controlled outlets match up nicely with a single RelayDrive module.

All source can be found in the HydroBot repository, including firmware source code and hardware files. The BOM and generated gerber files are also included for easy replication.

AirSense is a HydroBot module designed to measure air temperature, relative humidity, and barometric pressure. It uses the Bosch BME280 atmospheric sensor to take measurements and sends the results out over CAN. The module can measure temperatures from 0 to +65°C with ±1°C accuracy, humidity from 0 to 100% with ±3% accuracy, and pressure from 300 to 1100 hPa with ±1 hPa accuracy. Three LEDs indicate device status, CAN activity, and error states.

AirSense Features:

• STM32F0 microcontroller
• Bosch BME280 atmospheric sensor
• 6-30V input works with 12V and 24V systems
• JST-ZH series connectors
• Parallel bus connections for daisy-chaining
• Protofusion pogo programming interface
• Open source design

The default firmware uses a CAN baud rate of 500K and sends out messages on ID 0x201. Temperature is recorded with 0.01°C resolution, and is sent in bytes 3 and 4 of the CAN message data. Humidity is recorded with 0.01% resolution and is sent in bytes 5 and 6. Pressure is recorded with 0.1 hPa resolution and sent in bytes 7 and 8. By default, sensors readings are taken every 100ms, and a message containing averaged measurement data is sent out once every second. Future firmware work will add module configuration over CAN with settings including CAN baud rate, CAN id, data frequency, sensor calibration, and more.

All source can be found in the HydroBot repository, including firmware source code and hardware files. The BOM and generated gerber files are also included for easy replication.

HydroBot is a modular control system for automating hydroponic gardens. This system is designed with three objectives in mind. First, it will facilitate optimal growing techniques by using scheduling and feedback control loops to maintain state and adapt to changing conditions. Second, it will simplify controls interfaces, making setup and use easier for less tech-savvy gardeners. Finally, the components will be designed in a modular way to increase flexibility and support every imaginable garden configuration. HydroBot aims to bring sensors and actuators together through automation, which will allow hobby growers to focus on growing and not on constantly monitoring and adjusting the environment to keep their garden stable.

Why hydroponics?

NFT Hydroponic System

As the world population continues to grow and become increasingly connected, more attention is being focused on the disparity in living conditions across the globe. The further technology advances, the harder it is to believe that people in many parts of the world still struggle with attaining basic human necessities such as access to clean water and sustainable nutrition, and yet these issues remain unresolved. Addressing these problems will require collaboration from the global community, and I believe that hydroponics has the potential to be at least one part of the solution. Let’s look at the reasons why hydroponic gardening is superior to traditional agricultural methods.

• Hydroponics requires less space than traditional gardens when taking advantage of vertical space by stacking growing systems on top of each other.
• By tweaking the environment and nutrients given to the plants in real-time, hydroponics can speed up the process of growing plants by as much as 50% [1].
• Because the system is closed-loop, hydroponics can also use up to 90% less water than traditional farming methods [2].
• Plants can be grown year-round, increasing space utilization in the winter months.
• The absence of dirt means produce is cleaner, and the clean environment means less bugs to damage the crop and no weeds to worry about.
• With greater control over the nutrients being fed to the plants, they can be grown to contain more vitamins and minerals as well as improved taste.

The biggest downside to hydroponic gardening is the cost and complexity of the system required to support it – and that’s where HydroBot comes in.

The HydroBot Vision

HydroBot looks to solve the problem of controlling a complex hydroponic system through automation, simple interfaces, and flexible design. Automation will be accomplished through the use of an embedded computer that will handle all the feedback control loops and scheduled tasks. The embedded computer will communicate with a server to provide data logging and an easily accessible remote interface. The server will also host a webpage with data graphs and user controls, and have to ability to send out critical system alerts. To make the system flexible, a modular architecture will be used for all functions that interact with the physical world, such as sensors and actuators. Each function will have a corresponding module to carry out that specific task and report back to the embedded computer, which will act as a central hub for these modules. A multi-drop communication network will be used to connect the modules to each other and to the central hub. A block diagram of this system architecture can be found below.

HydroBot Block Diagram

Implementation Details

Although each module will be developed separately as the need arises, there are some high level system design decisions that will dictate the requirements for the modules. CAN has been chosen as the primary communication network for HydroBot, because it meets the multi-drop requirement, works well over relatively long distances, is very robust to environmental noise, handles errors gracefully, and has built-in arbitration and message priority. Support for additional communication protocols may be added in the future as needed – for instance, if an application requires wireless communication. To make the system as flexible as possible in a variety of applications, both 12V and 24V power will be supported. Modules will also be daisy-chain-able and allow up to 1A of pass-through current. To keep connectors consistent, JST ZH series has been chosen for module connections when possible. To keep a consistent code base and shared libraries across modules, STM32 microcontrollers will be used as the standard for module processing.

Several key modules have been identified to fulfill the basic functions required in most hydroponic systems:

• Environmental sensor to monitor air temperature, humidity, and pressure
• Water reservoir sensor to monitor water level and temperature
• Relay driver to control pumps, lights, heaters, etc.
• Dosing pump driver to control nutrient mixing
• Nutrient sensor to monitor salinity and pH
• Light sensor to monitor grow-light output

The possibilities for module development are endless, and additional modules will be developed as they are needed.

Summary

Deep Water Culture Hydroponic System

Hydroponics may be a good solution to many of the world’s food-related problems, but the barrier to entry is still very high for most people. HydroBot hopes to solve that by creating an automated control system that is easy to use and flexible enough for any garden setup.

Sources:

1. https://www.hydroponics.net/learn/hydroponic_gardening_for_beginners.php
2. http://swes.cals.arizona.edu/environmental_writing/stories/2011/merrill.html

When you’re trying to grow a bunch of plants in a field where a water source is lacking, things can be a bit tough. Hauling water on-site is a very arduous process, even with a tractor/trailer full of buckets. After hauling 5-gallon buckets to water blueberry bushes for months, we began to work on a better reservoir irrigation system that was cheap and easy to automate with expandable capacity.

To store water, we decided to use a 55-gallon drum. The drum provides enough water for just over a week of watering every other day. We plan on adding another barrel with a siphon hose connecting it to the main barrel for additional capacity.

After deciding that a gravity-fed system would be inadequate, we purchased a very inexpensive 1250 GPH bilge pump. As cheap as it is, this pump provides enough pressure to water an entire row of blueberry bushes. If you are planning on a more extensive system, you likely need a more powerful pump (more about this later).

We added garden-hose threaded adapters to both the hose of our bilge pump and the intake of our watering line. Having a garden hose adapter for the bilge pump line allows us to use garden hose and sprayer nozzles to water other plants, if needed. Note that an in-line anti-siphon valve is necessary to prevent water from constantly flowing out–we eventually added one after these photos were taken.

We used standard black irrigation tubing and spray nozzles for our watering lines. This hose is incredibly cheap and the spray nozzles are about $.50 apiece. These nozzles are adjustable, allowing them to work with the very low water pressure that the bilge pump provides. Our watering hoses are laid on the ground, however lines can be suspended over plants on stakes if necessary (this help keeps dirt and other particles out of the nozzles).

We terminated the end of our watering line with a garden hose connector as well, mating nicely with the connector on the bilge pump hose.

We laid our tubing along the ground without stakes initially, however we ended up staking down the hose between every nozzle to keep it from moving around.

The setup itself is not incredibly unsightly and does a great job of watering plants in locations that don’t have a source of water close by. If the barrel is topped up every so often, watering is quick and easy.

Future Plans

In the near future (likely next season), I plan on adding automation to the system with a relay, microcontroller, and RTC chip. I am developing this system while at school for my small-scale indoor automated watering solution (documentation to come soon).

In addition, we have purchased an RV pressure-regulated water pump with much greater capacity, allowing us to water more plants and some of our fruit trees next season. If you need greater capacity for your watering system, you can buy one of these pumps for about $50 on eBay. If you need greater water capacity, you can add additional 55-gallon barrels with siphon hoses between them. This is an easy way to increase capacity without making any changes to your existing system.