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Hi James, very interesting. I wonder which Analog port on the mayfly you are using, ADS1115.?
One test I do, to verify the sensors response, is put the sensor in a simulated stationery stream, (jug of water) with a solar aspect, stable power supply voltage, and measure water temperature and water temperature together and see what it reports.
Water temperature sensors https://www.seeedstudio.com/One-Wire-Temperature-Sensor-p-1235.html
These sensors typically use a varying resistance with pressure change (water depth) and are influenced by temperature. I’ve seen some sensors that have nonlinear changes with temperature – depends on internal algorithms. The KIT0130 states it has temperature compensation, but not what the range is – but who can complain at the price.
Eyeballing your graph – its +-/10mm – but whats the temperature change. 🙂
One set of measurements I did on two individual sensors that where in the same family, with a stated temperature specification showed the non-linearity in some of the sensors. They where returned.
