I am using an API Filstar XP1 filter, with a 30 gallon aquarium. My problem is that the actual filtering is dismal (my aquarium has murky green water). I have done everything by the book (yes, I have the inflow and outflow in their correct places). For media, I use two sponges at the bottom (first the coarse, and on top of that the fine), and in the top basket I have two packs of carbonated charcoal. All the media is brand new (two weeks old, at the most), and I've been cleaning it once every three days, nor so. Is it possible it's not making it through the filter? Last time I cleaned it, the sponges just oozed muck, so something must be making it through. What am I doing wrong, because I am just plain out of ideas. Thanks