Svoberts,
One suggestion short of structural renovation/starting over, would be to address the naiad problem. I also have some older ponds that were completely covered with naiad and algae. I stocked the sometimes maligned grass carp in small numbers last year and added some Tilapia this year. On my 1/2 acre old pond (with two stocked grass carp and Tilapia) which was previously completely impossible to fish, it is now open, clear and free of both naiad and algae. On a larger, newer pond of 3 acres, the naiad has been clearly attacked but not sufficiently to my thinking. I only stocked three grass carp in the 3 acres along with Tilapia and that just isn't enough. Of course, The Tilapia are going to die off in the cooler weather and the grass carp will remain, but I'm thinking an annual stocking of Tilapia and a couple more grass carp is a far better choice than chemicals. Best of luck to your project.
