I am still hoping to get some input on what I would like to build for my 50 gallon tank. I have large rocks for aggregate and have a hard time cleaning all of the debris from between them. I plan to build a 3 drawer trickle tower which will be housed in a 30 gal tank under my stand. Would it make sense to have some sort of undergravel plates hooked to this so it would draw the debris from under the rocks into the filter? The way I imagine it working would be for the water to be siphoned from under the rocks, go into the top of the tower, flow through the 3 drawers of media into the 30 gallon tank and, once filtered, be pumped back into the top of the tank via a spray bar. I would have my heater in the 30 gallon tank also. I would appreciate any input on this as I would like to start constructing something. Also, if the power for the pump went off, would there be a way to stop the siphon if the water was being drawn from the bottom of the tank?