https://www.reddit.com/r/SpaceBuckets/ A community of 20,000 DIY indoor gardeners.

Subset from the SpaceBucket manifesto:

Humans of the Earth! Hear the Space Buckets calling. It is time for a DIY indoor gardening revolution. We stand at the vanguard:

    I. Bucket culture is open. We are a community of learners, a movement of tinkerers. Our goal is to spread information about how to grow plants inside small containers with artificial lighting. Anyone can join us.

    II. Bucket knowledge is free. We believe in the free flow of ideas and the unparalleled power of the Internet. We are part of the web, and we contribute to it. Profit is not our motivation, innovation is.

Also found these:

[1] http://hmeter.sourceforge.net/

[2] https://www.3dponics.com/ ( a 10,000 person community )

[3] http://yieldbuddy.com/ An open source automation system for hydroponics

[4] http://www.powerhousehydroponics.com/crash-course-open-sourc...

[5] http://scienceinhydroponics.com/2013/02/the-first-free-hydro...