The water level in my sump keeps going down...

[PEA]

I find that my sump level decreases because of my overflow get clogged. So the water level in my overflow rises. Or my water level in my display rises as the "fingers" on my overflow get clogged and doesn't flow as well, so when I clean it, the water level in my sump rises by a few inches. So you might want to check your overflow as well.