Really, if you use gravel with the undergravel filter, I don't think that it has the surface area that it needs, reverse flow could prevent the buildup of detritus to some degree, but I think you would still have some areas of low flow that would allow detritus to settle, or fall through the cracks as broomer illustrated above. The sand seems to be working well, the only thing you have to put some thought into is what material to use to prevent the sand from falling through the plate. I definitely believe there are still good uses for the UGF, especially as an Under Sand Bed filter. JMO