Last week, while I was in NYC with my daughter's girl scout troop, my husband decided to look at our big filter. It is a skimmer attached to a 1200 gph pump and canister filter. He found remains of a deceased fish inside the pump. Apparently the tube from the skimmer to the pump had split in several places. So the water was pulled into the pump unfiltered, and unfortunately my four smaller fish were pulled in to their death. So he pulled the apparatus out. I spent an entire day scrubbing out algae. I cleaned my two box filters five times and I did a total water change. It looks much better.