So I've completed a lot of testing with temperature sensors and ultrasonic sensors as well as program logic. Currently, the FLOPR computer will log temperatures of the Main Tank, Sump, and the room. It takes a measurement of ATO water remaining and calculates how many days are left before the reservoir runs out. The measurements are taken hourly, and every 24 hours, a report is compiled and emailed to me, and I get an alert text message to tell me a report is available.

I'm working on getting a version of the code that I'm able to put on github. There's a lot of specific information like account names, passwords, numbers that I'll have to edit out to provide a publishable version. I'm also trying out making a configuration file that the java program reads to set variable parameters.

I condensed down the rat's nest of wiring to a project box with a few simple break out boards connecting to the GPIO pins. The HC-SR04 ultrasonic sensor requires a 1k ohm resistor inline on the echo pin, and a 2k ohm resistor from the echo to ground. Vcc is 5.0v. For the DS18B20 temperature sensors, a 4.7k ohm resistor ties the signal and the 3.3v Vcc pin. Here are a few build pics:

Ultrasonic board:

Temperature board:

Ultrasonic board trimmed and mounted:

Completed temperature board:

Boards mounted: