osmolater issue

[Lordhelmet]

First off I want to say this is truly a great top off. Well worth the price for the quality achived.
the problem I am having is this unit was purchased new about a month ago. About half the time everything is normal. The other half of the time the water level reads normal but it is actually low by a few inches. If I splash the eye when it is like this it starts toping off like normal and fills right up. Any idea why that is?

 

[rvitko]

I would guess that water or some sort of debris is clinging to the sensor. Check first that no calcium film has built up on the sensor, if you are adding kalk or have the effluent of a calcium reactor near by this could be a culprit. A soak in vinegar for a few hours will solve this. Check that no algae or small snails or bits of sand or even possibly chunks of styrofoam form the packing of a fish or coral is stuck to the sensor. Check that the optic sensor is installed in such a way that water isn't cascading over the sensor or sticking between the glass and the sensor.