hey mike. i have 1 acre pond 2 and put in 7 carp as you did and three years later its worse than ever. i have chara and american pondweed. sucks cant even fish in the pond!! it cost 1000's of dollars to fix it(chemicals) and it will come back the next year unless you spend 1000's more with the pond guy mag. to aerate it and chemicals every other month. i gave up. plus i dont have time to mess with it all the time. good luck man i hope you can fix it.