i don't know if your water levels will be maintained with only using the filter media as a bubble trap.. cause i think that the water will just flow right threw it and have the same water level through out the whole tank.. you might be able to add some baffles of acrylic and inbetween but the filter media instead of using the eggcrate as baffles. that way you will have differrent water levels in the sump versus all at the same level....