I took a design that someone had linked to here and after setting it up it allowed some floating waste to get through to the float troughs. so all I really did was raise the gravel filter portion up and extended the intake below the gravel. As the water slowly swirls around from the bottom the heavier stuff settles to the bottom that which floats gets caught in the gravel or 3M scrubber filters before rising further to exit to the float troughs.

My current system is basically a very small experimental size. to which I have been learning the ins and outs and other problems of Aquaponics before I invest in a large commercial system. at this moment I did not b\put in a clean out valve. but I will at net cleaning.

though a picture may not help but a cut out or see through drawing of your /funnel/cone design might give us a good idea.