I used these mats for a couple of years and was not impressed..When I went to do my spring cleaning they were such a mess and I didn't think they helped maintain clear water. The last 3 years I have not used them and did not notice any difference in the pond or the fish. In fact, my pond is clearer than ever this year. I do use a filter with a UV light. To me, a big waste of money. My pond is about 1700 gal.

Thank you very much! That's what I needed to know.