Gill recommend 7010 Liquid Level Sensor for all new installations:
View 7010 Lightweight Level Sensor
The Rxl Stainless-steel Liquid Level Sensor is a capacitive level sensor for measurement of corrosive fluids in large tanks.
The sensor features the same standard SAE 5-bolt mounting pattern as the shorter R-Series Stainless-steel Liquid Level Sensor, with additional mechanical strengthening features on the underside of the flange to support the longer sensor probe length.