please be more explicit of what you need.....
do you want something that will fill you a tank? like have 2 sensors on a tank, one up and one down, so that when the level descreases to the bottom, the tank is filled up to the sensor from the top?
well what im looking for is a sensor that will detect the level and at programable points say six point it will turn relays on so other devices will operate
Quantum has proximity sensor ICs. https://www.qprox.com
Their QT310 is a fluid level device.
**broken link removed**
They have many application notes & a users forum.