I have a new 55 gallon tank about 6 months old. I got the filter from the pet store guy that was recommended and all was well. I do have one oscar, two catfish, two clown loaches and two plecostimids (sp?) they are rather large about 8 inches each. The problem started a week ago when the water was so clouded with algae even after a 25% water change. I did a full tank clean and now 3 days later, it looks like lake water! Could it be the new filter. I change the filter pads every week! Is there something I could add to the water to clear it up without nuking the fish?