Our 5 acre pond has always had a thick green look to it, but up close the water is relatively clear (you can see bream beds in 2-3 ft. of water). My mother, against my strong advice, introduced water lettuce - "its just 2 or 3 plants, it will be ok..." she says...
Well, before teh water lettuce covered the entire pond, it did a good job of clearing things up. In the early spring, before the stuff got growing good, the pond looked fantastic.
So... try adding some water lettuce, assuming your pond is small enough for you to physically remove each and every bit of excess lettuce and burn it.
Note... a section of chickenwire fencing dragged between 2 small boats with electric motors makes a good "rake" for the surface of a pond.