Many people dream of having a beautiful salt water aquarium with living coral in it. These tiny ecosystems, commonly referred to as reef tanks, are a bit more complex to set up than their fresh water cousins. There’s a whole lot more to it than simply dumping some water in an aquarium. Each one is a carefully balanced system that can maintain the life of the coral by emulating what the conditions are in their native reef. You have to keep an eye on temperature, light (both quantity and wavelength), salinity, alkalinity,  and even turbulence of the water.  Even simple versions need a considerable amount of care, and many people opt to go the opposite of simple, in order to maintain more fragile and beautiful creatures.

We found this project at Maker Faire Bay Area 2017!

Ranjib Dey has an affinity for these set ups and has been constructing a system to automate many of the tasks required to keep a reef tank healthy. There are already reef automation systems out there available for purchase, but they can be quite costly and are often closed systems, not capable of being modified. Plus, we’re makers! We want to build it ourselves. Luckily Ranjib has shared all of his work up to this point on his Github.

A nice web interface for your reef tank

The project is ongoing, and expanding, but currently has the following features:

  • AC 110/220v equipment control (on demand and periodically based on timers)
  • DC pump velocity and LED based light intensity control (using PCA9685 PWM driver)
  • Dawn to dusk lighting setup
  • Temperature and similar sensor (pH, ORP etc) integration using MCP3008 analog to digital converter
  • Automated photo capture (using Raspberry Pi camera)
  • Touch screen and web based interface (allows for directly controlling the Pi using touch screen or by accessing the web UI from mobile or tablet)
  • Adafruit.io integration (temperature and similar data will be sent to adafruit.io, where users can build their dashboard/triggers etc)
  • PID controller is integrated to allow for temperature regulation and other failsafe measures

The unit itself

You can find the complete Bill of Materials here, to build one yourself. It is really only some relays and analog to digital converters, plus the Raspberry Pi 3. Keep in mind though, this doesn’t include any of the actual reef tank itself. When you get into the components to keep the tank alive, you’ll find that lighting and filtration can end up being quite costly.

Sometimes, you can learn a lot about how a project is going by following what the peers in the community say about it. Here is a thread on a reef tank forum where Ranjib is sharing his progress and the feedback appears to be largely positive. Something to note here is that when people are discussing reef tank sizes, they are comparing them to… reefs. So even a 50 gallon aquarium is somewhat small. What Ranjib is using in his examples is a nano or pico tank.

Using a tiny aquarium is actually better for testing, as the temperature and salinity can swing at a much more rapid pace than in a larger aquarium. This makes having a tiny reef tank a bit more difficult than a big one, but also makes them perfect for Ranjib’s tests.

Of course if you just want to see some pretty pictures of Ranjib’s coral and critters, he maintains a Flickr full of macro shots. There’s plenty there to enjoy.