I went with a skimmer as I have plenty of trees around. If you have fish a waterfall with a filter would be worth it, I think. I have seen pumps that sit in the pond and pump to the waterfall if you don't want a skimmer. I'm sure people here with a lot of experience having fish will have great advice on filtration. I have five small fish in my pond, and can tell that a filter is needed. The threads here have given me great advice as I read through them. I'm sure someone here will have even more advice on pumps and filters without a skimmer. There is a learning curve to building g a pond, but it can be done, and is well worth it when done. I can't remember who on this forum uses quilt batting as a filter around her pump. As I said there is a lot of useful information on the threads here.