Hello @Campergeek! I am taking similar approach as you. Last year I've found an old foil greenhouse in my house attic and decided I will use it to grow some chillies. I have some experience with chillies, but not with hydroponics.
So here is my progress so far. Maybe we can share some ideas.
I do not want to build complete PFC, because of complexity, cost and small size. My plan is to start with simple system, few sensors and lot of manual work and as I get more experienced I will add more sensors and automation.
The idea is to make several boxes (3 meters long, 30x30cm) with growing medium (perlite or expanded clay). Flood and drain hydroponic system. It is quite simple to build and operate.
The flood and drain needs only water reservoir, pump and some timer. I already have fountain water pump which I got for free. The 100 litres reservoir for water will be buried in ground (I think this will help to insulate from fast temperature changes). For timer, I will use my Arduino-compatible electronics I designed last year for one project.
It contains ATMega328P and it can be connected to RS485 bus. I can connect several of them to one bus and then to Raspberry Pi. Each electronics module will be autonomous, It will switch on and off pump, measure temperature of water and air, later I can add EC/pH/light/etc... sensors.
The Raspberry will be bus master and it will read measured data and check if system is working. I plan to run OpenAG brains on this Raspberry, so I can use database and web front-end. Right now, I am waiting for RPi3 to arrive so I can install ROS and OpenAG brains on it.
At first I plan to use OpenAG only for measuring. The automation will be added later. I do not plant to use light or heating/cooling in my greenhouse but I think it would be possible.
As for nutrients, I plan to use FloraMicro with FloraMato. The water will be from well in my garden (it should be quite soft water, but I have to check first).
I have time until next month, then I have to start growing seeds in rockwool cubes. I think it will take until March/April (?), then it will be time to move it into greenhouse. So I have few months to prepare everything.