It is based on an electronic or mechanical principle detecting a magnetic field.
It can detect with no contact the presence of a magnet and gives an ON-OFF signal to the control system.
Level sensors in polyamide can be used in low chlorine water only (like swimming-pool).
In this kind of liquid this is better to use polypropylene level sensors.
For this kind of problem you have to put the sensor into a system anti wave.
This system is made by a closed tube with 2 holes (for air evacuation when the level goes up inside tube).
Smaller the holes are; bigger is the difference between real level of tank and level inside the tube.
Main advantages are the following: