Do you mind sharing the depths of sand you tested? I have always tried to stay under a inch. Although the 180 had a 2-3 inch sandbed(which is supposed to be a no no but I had no ill affects that I could see/test). The sand bed I am now using is 1/4 inch just for looks.

Along with what Karin asked- Do you have a fuge setup in the system? If so, how big?