The Decider


The Coreconduit: Garden Controller System was the first version of the hydroMazing project .  The author of the Instructable drones on and on about healthy plants requiring attention and boredom until,

“…I’ve programmed into the Arduino a function I called, “TheDecider” that makes decisions based on maintaining optimum environmental conditions for growing plants. I added 2.4Ghz Wireless Radio Transceiver modules and a modular receiver system so that data is transmitted to within 1000 feet.”

TheDecider” was originally hardcoded with specific values that were fixed in place until I changed them in the Arduino sketch, recompiled, and uploaded.  There are two types of decisions that TheDecider executes, timed-based, and sensor-based rules.  The time-based rules simply compare the current time to the last time the appliance was turned-on or off.  The sensor-based rules use a minimum value threshold and a maximum value threshold that are compared to the current sensor reading and then execute the corresponding action for the appliance.  For example, if the temperature is below 55° then turn-off the ventilation fans; if the temperature is above 80° then turn-on the ventilation fans.  Each appliance has corresponding rules for sensor reading thresholds, time-based automation, and a combination of both, priority depending on the order of the rules.

Today’s hydroMazing uses the Raspberry Pi to provide an interface to the rules and the notifications.  The Pi communicates with the Arduino Nano microcontroller wirelessly sending updates and receiving data. TheDecider is a rules engine that executes the checks sent to it from the Pi.  The settings are stored in the EEPROM of the Arduino Nano allowing it to operate without further communications with the Pi.  hydroMazing doesn’t require an Internet connection to operate with the exception of receiving emails or text-alerts.  The Raspberry Pi can be configured to operate only within your WiFi network and be allowed to send emails and text-alerts.  Or, you can configure your router to allow access from outside and even assign a domain name, such as  See my Instructables for steps to a secure Pi.


hydroMazing Nutrient Controller

hydroMazing outside the box
hydroMazing outside the box

The hydroMazing smart garden system is designed to monitor and manage your growing environment by automatically controlling fans, heaters, lights, water pumps, and now, the nutrient solution.

The nutrient solution level of the hydroponics container system must be monitored.

As the nutrient solution level decreases it needs to be replenished with fresh water, otherwise the nutrient solution becomes more concentrated and some plants won’t respond well.  The hydroMazing Nutrient Controller can activate a pump that adds fresh water to bring the concentration back to the level it was when started, often referred to as “topping-off.”  The hydroMazing Nutrient Controller will also monitor your pH and EC, activating pumps to manage the solution, and notifying you when you need to make changes.

There is no need to adjust your pH or EC until it is necessary.

This is a big one!  There is a lot of misinformation out there about keeping the pH and EC regulated.  If I were paranoid, I’d say it was a conspiracy from hydroponics manufacturers and retailers who want to sell more consumable product.  Don’t get me wrong, proper pH and EC is important, even critical, to the success of a plant.

The pH of water is an important measurement whether you are gardening indoors or outdoors, soil or soil-less, because it affects whether a plant can properly take in nutrients.  Even though hydroMazing monitors your pH and EC, I still recommend a handheld pH tester such as the Oakton EcoTestr pH 2 Waterproof pH Tester, which is excellent for the home gardener and has been proven time and again to be accurate.

The electrical conductivity (EC) of water estimates the total amount of solids dissolved in water, or TDS (Total Dissolved Solids). TDS is often measured in ppm (parts per million). In hydroponics, this measurement is used to determine the approximate concentration of nutrient solution to water. There are many hand-held EC devices available as well.

When do I need to adjust the pH?

Only under the following conditions:

pH is at or below 5.0 or above 6.5

AFTER at least 30 minutes from the time of topping-off or changing the nutrient solution.

How to adjust?  I highly recommend using pH Up and pH Down from General Hydroponics sparingly and only when necessary.


Flushing means to literally flush empty the nutrient solution from the hydroponics system and replace it with fresh “good” tap-water.  Then return the nutrient solution back to what it should be for the phase of growth.

When in doubt, flush the system and refresh the nutrients.  Otherwise, it’s recommended to flush your recirculating system every 7 – 14 days.  When I grow, I try to keep the nutrient solution working as long as possible, however, salts build-up over time and it is good to flush with fresh water from time to time.

What’s Next?

Using a Web Cam to Monitor Your Grow

What is a Smart Garden?


The hydroMazing controller is designed to operate ventilation fans for air circulation, water pumps, occasionally a humidifier, heaters, or any other appliance that is necessary to maintain an ideal environment for plants to grow.  Typically, we DIY’ers would hook-up some relays to a microcontroller to achieve control.  However, with hydroMazing, the system uses remote controlled wireless AC outlets, ensuring safer control than traditional relays.  hydroMazing uses low-cost open-hardware modules and the ubiquitous microcontroller, the Atmega328, on an Arduino Nano*, offering the flexibility of customization and expansion. The sensor choices are endless, but I’ve narrowed it down to a few important and relatively inexpensive modules.  A temperature and relative-humidity sensor, moisture sensors for soil, liquid temperature probe for hydroponics, a simple photocell.  There are many other optional additions including the float switch or switches and flow-rate sensors.

The wirelessly controlled outlets proved to be a etekcity_outletsreliable method of controlling the fans using the Arduino to send the signals depending on the temperature sensor’s readings.  It didn’t take long for the source-code to evolve into a beast.  The Arduino family of microcontrollers is limited in how many instructions it can run and hitting the program size limit doesn’t take very long when you want to control more than a few blinking LEDs.  I have found that the size limitation has forced me to write better, more efficient code than I initially do.  Even with creative variable handling and custom libraries, eventually, there is a need for another microcontroller or to move to a larger one.

Wireless Monitoring w/o Internet

There are several ways that the microcontrollers can communicate with each other.  The least expensive wireless method I could find is the nRF24L01 wireless radio transceiver. The module is a low-power, lightweight variety of bluetooth giving hydroMazing the ability to communicate with a monitoring unit.fpzexmwi7vqs7mr-medium

I decided to add another Arduino Uno with an Liquid Crystal Display shield so that I could display what the sensors were reading, the state of appliances, and alerts with notifications.



I made my own open and adaptable platform that can be custom tailored to a wide variety of gardening needs and conditions; yet, also a self-contained wireless system.  The open-architecture of the system allows for ease of integrating Internet connectivity and web services.

Internet Monitoring

Enter the Raspberry Pi connected with an nRF24L01 module.

I was able to modify much of  my Arduino Source code to listen for incoming transmissions and then write that data out to a few files.  First, a log file that captures all communications between the Pi and the hydroMazing Monitor.  Next, I have the program write out the current state of all sensor objects and a file for all of the appliance objects.  When an alert occurs the progrhydromazing-liveam will create a file containing that alert.

I then added a PHP script to read in the data object’s from their respective files and display live on the Pi’s Apache server.


Next, I wrote a Python script to read the directory for the alerts file and if it exists, read the file, parse out the pertinent information and then email or through SMS text the user.  In addition to sending an email or text alert, the python script moves the alert file into position for the PHP script to read and display.

Using the log files that are created, I am able to import the data into a database.  Once the hydroMazing’s data is recorded into a database residing on the Raspberry Pi we can start performing analytics and generate some reports.

Monitoring and controlling the system is mostly done for us, but when the hydroMazing needs to alert us to a problem it can now by using the Raspberry Pi.



With the hydroMazing smart gardening system, you can grow healthy, happy plants anywhere!

Contact us today for more information!