Hot Tub/Spa & Pool Water Quality Sensor

• Solar powered
• ORP & pH Sensors
• Estimates Sanitizer ppm
• Home Assistant Integration
• Firmware is using esphome

Hardware

• UM FeatherS2 ESP32 board from here
• 2500 mAh
• Atlas Scientific Gravity Analog ORP and pH Kits
• Enclosure: DS-AT-0811-S
• 2x100 kΩ resistors for battery monitoring (optional)

Solar Panel Components

• Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger - bq24074
• 3.5mm / 1.1mm to 5.5mm / 2.1mm DC Jack Adapter
• Small 6V 1W Solar Panel
• JST-PH 2-pin Jumper Cable

Wiring

• Diagram
• NOTE: You can skip the ambient sensor removal step

Firmware

• Install esphome (Tested Version: 2023.12.5)
• copy wifi_example.yaml to wifi.yaml and edit the new file
• Connect the board via USB and enter esphome run tubby.yaml on the command line. This will build and upload firmware to the board.
• In Home Assistant, create a helper switch input_boolean.ota. Enable this switch, it will prevent device Deep sleep.
• Power cycle the board, Device then enters Light sleep for 15 minutes before it shows up in Home Assistant
• Once your esphome device is added to Home Assistant, Use Device's page, Diagnostics section to calibrate the probes:
  • ORP Cal : mV ORP calibration offset from raw ADC value. Note: ORP mV Sensor value has calibration applied
  • pH 10 Cal: mV reading from pH Raw sensor while submerged in pH 10 calibration solution
  • pH 7 Cal: mV reading from pH Raw sensor while submerged in pH 7 calibration solution
  • pH 4 Cal: mV reading from pH Raw sensor while submerged in pH 4 calibration solution
  • ppm Factor: 1 - Chlorine, 3 - Bromine
• Turn off input_boolean.ota to allow the device to save some power.
• Place the probes in the water, and enjoy!

Sanitizer ppm Model

• pH + ORP -> Chlorine ppm Conversion Table
• Machine Learning Notebook
• Generate .h file from .tflite: xxd -i model_fc.tflite > model_fc.h