Arduino Aquaponics: Water Temperature

Introduction

Two important parameters to monitor in an aquaponics system are the water temperature of the fish tank and the root temperature of plants in the grow beds.  In fact, soil temperature is far more important than air temperature when it comes to a plant's ability to grow and uptake nutrients.  By monitoring both the stock tank temperature (origin) and the grow bed temperature (destination) you can see the thermal efficiency of your plumbing system or connect it to a  relay to create your own water temperature controller. A great sensor for monitoring temperature in liquid environments is the waterproof DS18B20 and it's very easy to connect to an Arduino.

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Arduino Aquaponics: Temperature and Humidity

Introduction

This sensor is the DHT-22 which senses the temperature and relative humidity of the surrounding air.  The DHT-22 is pre-calibrated at the factory, with the calibration information stored in an 8-bit computer inside the unit.

Air temperature is measured in Centigrade, with a range from -40 to +80 degrees and an accuracy of 0.5 degrees.  Relative humidity is measured as a percent, with a range of 0 - 100% and an accuracy of 2 - 5%.  A downside to this sensor is the sampling rate - measurements are can be taken once every two seconds at most.

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Arduino Aquaponics: Real-Time-Clock

Introduction

At the heart of any control system is accurate time tracking.  This tutorial shows three ways of using the RTC.

• Getting the current time
• Using the time to create intervals
• Doing something at a specific time

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Arduino Aquaponics: Overflow Sensor

Introduction

Overflow sensors are just about the easiest device you can make.  Essentially, the design is similar to a switch, wherein the flow of electricity through the circuit is broken.  An example application is aquaponic grow beds being flooded: when the water level meets both probes, the circuit is complete, the flow of electricity resumes and is detected by a digital pin as an overflow occurring, which in turn can shut off the pump.  A state change of the pin, from LOW to HIGH or HIGH to LOW prompts an update to Tracker and, if the new state is HIGH and you want alerts, sends an email alerting you to a potential overflow.  The probes used in this tutorial are stainless steel machine screws to minimize corrosion, and they are inexpensive and easy to replace.

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Arduino Aquaponics: Relays

Introduction

One way to take any Arduino project to the next level is by using relays.  Relays are essentially mechanical switches, except they are electrically controlled and, therefore, can be controlled by an Arduino.  Many devices used in aquaponics have on/off states, such as pumps, grow lights and fans and therefore can be controlled with a relay.  This project will simply turn the relay package "on" and "off" without hooking up any additional hardware (like an aquaponics pump); we'll save that for other specific tutorials.

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