Aquarium Monitor: Water Temperature and pH

Fish are sensitive to small changes. A waterproof DS18B20 probe reads temperature over the Pi's 1-Wire bus, and an analog pH board read through an ADS1115 tracks acidity. Together they catch problems while you are away.

Mission steps

1. Enable 1-Wire

   Add dtoverlay=w1-gpio to /boot/firmware/config.txt and reboot; the probe's data wire goes to GPIO4 with a 4.7 kΩ resistor to 3V3.

2. Test the temperature

   The probe appears in /sys/bus/w1/devices as a folder starting with 28-; the script reads its temperature file.

3. Add the pH board

   Power the pH board and ADS1115 from 3.3 V and connect the board's analog output to ADS1115 input A0 (I2C to GPIO2/GPIO3).

4. Calibrate pH

   Dip the probe in pH 7 and pH 4 buffer solutions, note both voltages and compute a straight-line conversion.

5. Set alerts

   Warn when temperature leaves your species' range or pH moves more than 0.5 from normal.

Code

import glob, time

probe = glob.glob('/sys/bus/w1/devices/28-*/temperature')[0]
LOW_C, HIGH_C = 24.0, 28.0      # set for your fish

while True:
    with open(probe) as f:
        c = int(f.read()) / 1000
    status = 'OK' if LOW_C <= c <= HIGH_C else 'ALERT'
    print(f"{time.strftime('%H:%M')}  water {c:.2f} °C  {status}")
    time.sleep(60)

Tip: test every script on the bench before installing it in a moving machine.

Questions