We are currently developing Veleda, an open source, open data platform for hydroponics. We have a live data view of the state in our greenhouses. We develop the software and hardware (ESP8266) behind it and are in the process of extending it with additional parameters.
Parameters for which we are building low-cost sensors range from air and water temperature to pH and EC values, from biomass to image derived plant health. The server side source code is available on the Github page and we will be releasing the hardware in the coming weeks.
The project is based in the Protohaus and sponsored by the city of Brunswick.