Backyard Aquaponics
A place to discuss aquaponics

hi charlie!i understand your confusion,caused by the foam leftovers on the top of the filter shown at the picture.
The actual funtion is described at the cross section below


The water goes down to the bottom of the barrel through the center pipe.There is some gravel.As the water rises up to the barrel outflow it is filtered by the foam-coarse which is cut to fit the whole barrel surface.Solids have not a way to pass the foam-coarse and stay down.
Foam leftovers are thrown at the top to provide some extra space for the bacteria.
I hope i explained it good enough for you to understand.I will take some more accurate photos in the next days.Any further questions are welcome!

yep thanks for that, it is what I had expected.

cheers