That's rough.
One of my dads ponds (about 4 years old now) has a big problem with grass/algae. It's about a 7 acre pond. It's near a big hog farm, and right next to a farm where they inject manure in the ground for fertilizer. I don't know if that runoff has anything to do with it or not.
It loses a lot of water in the summer, grass grows around the edges, then it fills up in the winter/spring, covering up the grass that grew in the previous year. That probably doesn't help.
The water is also really clear - lots of sunlight penetrating doesn't help. (he added aqua shade)
He talked to a guy a couple of weeks ago about digging a well for it to keep it full. Guy said it'd be 2 years before he could get to it!
The entire bottom is covered in algae-sort-of grass. You can't fish anything Texas rigged in there. You have to stick to moving baits (no treble hooks) or top water.
On the positive side, the bass are thriving. Biggest we've caught this year was 5.14 (post spawn!) not bad for a 4 year old pond.
Our biggest five fish Saturday topped 20lbs easily.