Pressure reading seems to track temperature

[NickWaterton]

I have been having problems with accurate readings from several BAR02’s. I am measuring the water depth in an outdoor water fountain tank (20cm deep).

I finally plotted absolute pressure (Bar02 - atmospheric pressure measured with a BMP280) vs water temperature, measured with the BAR02. There is an exact correlation.

In the attached, there is rain at midnight, and the water pump switches on at 8:00am and off at 10:00am. The jumps in water pressure is reflected in the changes in water depth of the tank.

I have tried two different BAR02’s with the same result. It’s as if the temperature compensation is not working. The library init’s just fine though, so the CRC is correct. I have checked the math, and it corresponds to the datasheet.

Something is not right though.