Sand filter questions...

[tmcmaster]

So, I was reworking my basement system, and trying to install a fluidized sand filter, but ran into a few issues. It seems that the water from my radial flow filter is NOT draining into the sump, where this sand filter lives. The filter itself is constructed of a 10 gallon glass aquarium with about 2-3 inches of sand, followed by 4 inches of 1/4 - 1/2 inch river stone. (See image) The inflow pipe is 1 inch PVC.

[attachment=0:2zc5e586]Sand filter.jpg[/attachment:2zc5e586]

Some questions I have:

• Is it possible that without a constant inflow of water, the sand could be clogging the in pipe?[/*:m:2zc5e586]
• Is the vessel I am using possibly to blame? (The 10 gallon aquarium)[/*:m:2zc5e586]
• Should the entire sand filter NOT be below the water level of the sump itself. (Sump tank is 3/4 of a 55 gallon drum)[/*:m:2zc5e586]

Any help would be greatly appreciated.

Thanks!!