Nice, very nice. As for gravel cleaning, maybe some kind of a plate that it sits. Then make the plate aggitate some and then some kind of a force of either air or water jets on the bottom to push the debri from one side of the tank to the other. Sort of like the way a river pushes debri and sediment from the river top to the river bottom, just have it drain out a screened tube into a drain. Now that would be cool to incorporate that. I know, my imagination is out there. But that would be cool as heck to see.