For the past 3 months eveything has been fine with my overflow and sump but I just noticed that my water level in my display tank has actually risen to were its almost overflowing. It used to come up to the lip on the top of the tank and just even with the glass support in the middle of the tank but now in the last 2 days it actually sits on the lip and goes over the glass. I cleaned the internal overflow boxes and dont see anything blocking the u-tubes or external boxes. I tried raising and lowering the inernal boxes but that doesnt seem to help either. I also shut off the pump in my sump but that didnt help. I dont like the water that close tp the top! any ideas??