I built a Pi2 powered aquarium system to monitor temperatures and control lighting. Python scripts and crontab scheduling read the water and ambient temperatures, sending an email notification via IFFT if the readings were out of range. The data was recorded in a MySQL database. This was accessed using a PHP web page on an Apache server. The PHP called a Python script to read the data from the database, graphing the output through a Google API.
Having discovered Cayenne this morning, I migrated the temperature monitoring to Cayenne. It was very easy to do, with no problems. I will migrate the lighting control at a later date. I may also automate feeding.
Temperature monitoring is via a pair of waterproof D18B20. One in the water, the other on the outside of the tank.
Blue and White 12v LED lighting is controlled by a pair of relays. Daytime = White, Night = Blue, Morning/Evening = dimmed Blue/White.
Email and SMS alerts are set if the water temperature goes outside set limits.
Scheduling will set the lighting according to set times of the day, although I would like to link it to sunrise/sunset times.