As far as the device receiving the sensor's signals, could they be received by something like this Sensor Shield? or is it better to handle the receive of sensor data by the RPi? Or is this more of a preference kind of situation? I was thinking of using the shield for the heating elements/lighting arduino at minimum, but if its better to have the driving arduino receive the information and then send relevant sensor data to the RPi for the database part...right now I've been thinking of the RPi recieving the sensor data and then talking to the heater/light arduino when changes/adjustments need to be made (the RPi will be the master of the l2C connection between them anyway.) @hayduke Well, the temp/humidity will likely be different enough from the room's temp/humidity to matter to the beings inside the vivarium (I actually have run my apartment's thermostat while I was fixing some heating arrangements to keep him whithin a healthy range...wasn't something I want to do long-term.) I may just run a long wire from the sensor to the nano, either using some single pins of cat5e I have lying around (since it would have a plastic sheathe already) or put it in some heat shrinkwrap. I went looking for electronics coating materials and I'm probably going to grab a couple to see which work best. From what I can tell, as long as I ensure the humidity sensor's input location stays 'clean', it should protect all the rest of the circuitry from the water mist. They'll be physically protected pretty well from direct watering but the floating water droplets that get in the little enclosure...I want to limit the chance of their damage. I will definitely be providing lots of pictures of the build I'm always big on credit where credit is due. @epierre As to the lights, I finalized my choice and thus had to make some changes in what I'll be ordering as they're 12vdc; 60W for the daylight circuit and 30W for the moonlight circuit. Thus, FET from what my research turned up and I found a board with 4 channels of IRF540-type power FET. The ones I'm going with are 'full spectrum' 80+ CRI (the 95+CRI ones I was eyeballing weren't flexible with lengths shorter than they advertised which would have run me about 1.5x as much as I'm already shelling out for these lights.) If they don't end up meeting the PAR of the plants, there's room for me to put a light in to supplement them. Just have to make sure they are atleast moderately easy on the eyes- full grow-tier lights would make the vivarium strange and really mess up the snake's senses since reptiles take cues off certain wavelengths as well (which was my driving point of getting a medium/high CRI lighting fixture in the first place.) I've also got a local electrician who will handle a chunk of the mains-wiring and hopefully be able to double check that I have everything properly protected against surges/shorts. I also found a 4 channel phase-control board for the ceramic heaters. Running the numbers to make sure they will work; I'm probably goign to skip the 200W CHE and switch to something like 3 or 4 CHEs of lower wattages so I can do a more even heat. Probably a 150W in a corner with rocks for a basking spot and then two 100W out another 8 and 16 inches out for moderate ambiant heat. Sanity check, 4 of the SI7021's (such as this SI7021 can be wired and controlled by one nano? Or do I need one nano for each sensor?