This is a Bluetooth (BLE) iOS app that receives water quality data from a corresponding Arduino project, adds a timestamp and GPS coordinates, and saves that data to a file/website.

Water quality data is logged from this sensor on the Arduino project:

• Atlas Scientific Conductivity Probe K 1.0

For more information see: water-quality-sensors

Then the iOS app adds:

• ISO 8601 formatted time, including the time zone.
• The position - latitude, longitude and accuracy.

I'm using the RedBear BLE Nano 2 for this project - the only limitation I've found so far is that it's a 3.3v board, and the rest of my project is 5v. Powering it via 5v is fine, but I need to step down the voltage on the serial line to the BLE Nano to avoid frying it.

This app is based on the RedBear SimpleControls example project.