I have a 1/2 acre pond....pretty old, with cottonwoods and spruce trees surrounding it. For the first few years after we moved here the pond was pretty clear, but as the years have gone by it 'appears' to have a kind of muddy appearance. It has a natural sand bottom....we live next to Lake Michigan in the sand dunes area.

It now has a covering of greenish brown....with a little red tint, of sediment sitting all over the bottom. I rake leaves out of it all year round when there is not ice on it and try to keep at least the edges of it clean. When I rake it out and the sand shows through the water is clear, but you can see this sediment lying on the bottom. It is light and moves around when raked, but settles on the bottom again....the water still clear on top of it.

I have no fish in it, but minnows, frogs, crayfish and turtles.
I use beneficial bacteria, muck reducer and algacide in it during the warmer months as soon as the water comes to 50 degrees. I don't know what else to do for it.

Could it be from the run off from the lawn which is fertilized....or is it from the decaying leaves? I almost want to say its some form of algae, but I treat it for algae all summer long. Any ideas??