I’ve used Atlas Scientific’s RGB sensor on lagrangian river drifters in the past. The application is written up in Limnology and Oceanography (or see this video abstract of the article). I’m attaching two simple sketches for using this sensor with the Mayfly Data Logger. The first (…AutoMode) just prints R,G,B, and Lux at an interval to the serial monitor. The …ManualMode sketch allows you to interact with the sensor using the commands from the datasheet. Please keep the EnviroDIY community updated on your progress.