I tried this method and it seems within a few hours the water level starts rising in my cup chamber. I tried a filter sock in the first compartment and then the cup/matrix/polyfil in the second and I watch the water level in the one with the cup start to rise. I’m concerned it will overflow. I tried the rolled up filter pad too and the same thing happens. With the mesh bags I have next to nothing in them after 4 days. My tank has only been up about a month and a half and has a very light bio load. Why do my cups start to overflow so quickly?Hey I do the same thing!