"That said, if you can find a suitable level sensor (eg maybe AquaPlumb from Vegetronix or eTape from milonetech.com) that can be adapted to deliver a 0-3v linear signal with depth then you could potentially interface it to one of the voltage inputs on a VP2 (eg solar or UV or soil moisture). That would potentially give you a suitable signal, but wouldn't read out directly in a suitable scale. An Envoy8X would make scaling easier - officially discontinued now but still available."
Ah OK thanks, yes I have a VP2. At what point is the signal 0-3v linear - that bit I can do OK but is that the actual sensor input? Calibraion no issue. Am keen to use this solution as have the VP2 networked and the tank is 300m away from the main station.