I recently picked up a nano cube 12 DX from a person on craigslist. Upon filling the tank, it seems that the levels in all three chambers and the main tank are all the same no matter how high I run the internal pump. I used to own a biocube 12 and a mini 2 gallon and it seemed in all of these that the water level in the chamber with the return pump was always lower than the other two.

Is the DX not designed to run this way?