My setup works fine with following combination of hardware: Raspberry Pi4 connected to a TCA9548A I2C Multiplexer from Texas Instruments, whereas each channel is connected over 4wires (GND, VCC, SDA, SCL) with 140cm 30awg silicone wires to two more I2C sensors.
In the office, the setup works perfectly. When the cables are immersed in water, which they need to be for the application, I get errors. Wrong addresses are displayed for the I2C sensors and it happens very very rarely that the sensors are recognized under their correct address and can also be read out.
My question is basically: How can I model the wire capacitance with regard to the surrounding water and maybe other relevant water parameters such as the electrical conductivity?