@Webb.Peter The foam worked out really nicely and is still holding up on all of the PFCs (we started building them ~16 weeks ago)! We used 2"-thick insulating foam from Lowe's and taped all of the pieces together using gaffer tape and Gorilla Glue Tape (3"-4") on the inside and outside seams of the box. We also left the top foam piece + attached grow light unattached from the rest of the PFC so we could reach into the PFC if needed. I'm not sure how much reflectivity the PFCs need for light, but it might be of interest to add mylar sheet on the inside of the foam if you need a reflective surface?
I added on the camera because I wanted to teach the students how to program with Python + Raspberry Pi (I think the language is a bit more intuitive than Arduino), and I also wanted the students to have an end-of-semester deliverable to show what they made in class (besides the actual vegetables). We culminated our coding "section" with learning how to code a gif in python, and then attached the camera + RPi to the PFCs and ran the code--I think the students really enjoyed seeing the time lapse of the plant growth, so I'd keep it in future iterations, although maybe not essential if you aren't using Raspberry Pi for other components. Perhaps the sensors and other automation can be connected to Raspberry Pi instead of Arduino in future iterations?
Ah! The cold water for spinach might've solved our problem! We did two rounds of germination: one inside the PFC and one outside the PFC. They both lasted for 1-2 weeks and then died. The inside of the PFCs got pretty hot because of the grow lights, and students measured the water temperature bi-weekly, which I think was around 23-28 C. Thanks for the spinach growing resource!
A few things (I think) weren't connected properly to the Aruduino including the humidifier, water gallon pump, and the fan, so we never actually used the humidifier although it was attached to the PFCs. Since the inside of the PFCs got pretty hot from the grow light, we kept the fan on constantly, and then checked nutrient levels by hand to replace when needed. Our lettuce and swiss chard grew nicely without humidifiers, so it's probably not necessary (at least for some vegetables). I also built a fourth Foam Farm to conduct experiments on my own, and grew lacinato kale nicely without a humidifier.
The peristaltic pump and never worked when hooked up to the Arduino, so I'm not sure if I accidentally set up something wrong in the code or if something wasn't connected properly? I haven't yet found anyone else who build this model of a PFC, so I'm not sure if this is my error or not. What additional information do you think could help you figure out what might have gone wrong?