Optical level sensor with salt giving false alarm

[almost]

My optical level sensor is 2 cm above the water level.
It shuts off the return pump in case of an overflow malfunction.

But..

2-3 times a week it gets salt from water evaporation and it gives false alarm.

How can I protect ir from getting salty from evaporation?

[Blahenazo]

are you sure its evaporation ?
and no water spray on the sensor , or salt creep because it get sprayed by bater
it could be avoided by making a protective holder or something.

and also if the sensor is 2cm above the water , why not use a cheaper floater ? it should be able to handle the salt more easily
and it will not get stuck by calc if is most of the time above water

[almost]

I am using both a floater & an optical sensor as an extra security.
If one goes down, the other will be also able to stop the return pump, so to avoid overflood which will be a disaster..

It is not sprayed by anything, there is nothing there ecxept the 2 sensors.

I am looking for a way to make a protective cup.. I think in Reef Central they have made one, but I can't find it now..