Water level indicator

[leman_opc]

I'm currently planning an install of hfs3 system on my Opel Astra OPC (=Astra VXR in Vauxhall range), and the best place for tank/pump we found is behind the front bumper.

With the tank installed there I'll be not able to see the water level (visually, so to say), so to have an idea when to fill the tank I need a water level sensor.

My question is - from the manual I'm unsure how the supplied water level sensor works. Does the sensor activate the failsafe immediately when the low water level is detected or there is a kind of intermediate state (water is low as indicated with a blinking yellow led on the gauge but the system still working yet with no failsafe on)?

Also, would be great to know the logics behind the water level sensor operation in hfs3 (the sensor itself appears to be a discrete output one so I would imagine hfs3 controller should have a kind of algorithm to filter out the low water level signals due to simple water movements back and forth on cornering etc.)...