Just to put my 2 cents worth in here, this looks like what I have every year. Here in the middle of Michigan we go through a number of problems called "spring". We get the "cotton wood fuzz", the maple tree helicopters, the pine tree pollen and a few other to boot! They all add something to the water, film, scum whatever. A good rain often clears it up, but a day of two later there is more. I am glad to see you all talking about this as I was concerned I may be the only one with these problems. The fish do fine, and I leave a bit of FA around the edges for the small fry, frogs and turtles. It doesn't look good but the fishing is, and we do not use it at all for swimming.