One of the powerheads im using in my cube is a maxi-jet 900. Initially i had set it up as the return pump for the cube and it was running fine and perfectly quiet. Just recently i switched it out for a different pump and moved the 900 into the display as a circulation powerhead and set it up using an impeller first, still running silent. Just tonight i switched it around and replaced the impeller with the propeller it came with, and while the flow has increased significantly...its got a decently loud buzzing sound now -- anyone else use this powerhead and have the same issue with the propeller?