Tunze 9004 skimmer?

[tmccaff]

I just got this skimmer and put it in my sump. Where should the water level be? I see a mark is that where water level should be? Maybe a stupid ?

 

[rvitko]

The water comes in from the intake under the cup, at least 1/4 of the intake should be submerged, but not more than half.