I have a waterfall bio-filter, a sweeper filter, and a Sequence pump. I also have a chemical filter on the water hose to rid all of the city added chemicals when filling the pond. All have been working perfectly since 2000 when I built the pond. I am down to 38 koi due to a pesky Great Blue Heron, and the pond is less than a quarter full of lillies. I clean my bio-filter once a year and I used to clean my sweeper filter once a week, whether it needed it or not. The sun has been tremendous this year. I have been using Algaefix according to direction, which has worked great in the past. This year I have added Microbelift to my pond. The cleaning of my sweeper filter has become intense this year. I have it down to a science now. I clean the damned thing EVERY EIGHT HOURS NOW! I need help, please.