Can anyone help with this? Have a pond in northeast Wisc. . Last year and now this year there is a green layer of something just barley under the surface of the water. Any waved seem to go right over top of the green stuff, if It rains it will completly disapear and come back in a day or two. I don't know if it could be pollen or something else. It's not a mat like some algae is. it alomost seems like powedery but its just under the surface like barely under the surface. Any ideas what it is or how to get rid of it?