Hi thanks for the inputs:
I have seen this >> http://www.open-electronics.org/water-tank-level-display-with-arduino/ working with a ULTRASONIC sensor , its successful but what about being successful in the 500 LTR tank casing it is very deep and wide? can you guys put some light on this method?
EDIT: But then WIKI says this about ultrasonic sensors "Ultrasonic level sensors are also affected by the changing speed of sound due to moisture, temperature, and pressures."
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