Raspberry Pi PH Circuit
The first section of this project was building the Circuit which would be used to pull the PH from the Hot Tub's water.
The sensor which I settled on was the PH sensor from AtlasScientific.
I initially (and purchased later) purchased the kit without the isolation circuit, but would recommend purchasing the isolation circuit to avoid interference the pumps can cause with the PH sensor.
The main reason for going with the v1 Raspberry Pi Zero vs the Raspberry Pi Zero W, was due to the fact that the UART communication on the Zero W had problems which made it unreliable for polling the PH sensor.
AtlasScientific provides some great data sheets which outlines exactly how the sensor functions, and how to obtain data via UARt and I²C as well as how to calibrate the sensor.
AtlasScientific also provides some code tutorials / samples which can be useful to get things going with setup and data polling.
The breadboard setup that was used for prototyping the circuit:
The schematic looks like this:
The next step was to pull the data from the sensor.