Passat--I realize that this is late in the season, but just another point of view. I had problems with the filamentous stuff and got rid of if by putting in talapia. I would think that somewhere you could find them in your area. I did a google search for "talapia-aquatic"...and found a web site for " Opposing flows technologys" that talks about raising talapia in Maryland. So I think that they could be found up north . But I guess that it depends on what your water temperature runs in the summer. They die off in cold weather , below 60 degrees , they get really sluggish and swim in the shallows, looking for heat, and you can catch them easily and eat them after they have cleaned up your pond. The Fish are very prolific. They are pellet raised in heated tanks, and ate their fair share of pellet food, once the algae was gone. I had no more problems with in two weeks of their introduction,and for the rest of the summer.I paid $ 10.00 a pound for mine. I put 15 pounds in my approximately 3/4 acre pond, in late april here in East Texas. This is what was recommended by the salesman, but I think that if I have to go this route again , I might try just 10 lbs. for my pond since they cleaned it up so fast, or start them earlier if fertilizing doesn't help enough.
Next year I am going to try and fertilize earlier to avoid the algae problem. Did not learn about this approach until to late, so talapia was the best approach for me. Do not buy grass carp as I did, they do not eat algae. They may eat most any other grasses that cause problems, but algae eating is not their forte.
I wanted to use some of the pond water to irrigate my flower beds, so I was not wanting the copper stuff to accumulate in the flower beds.
If you have any predators ( bass, catfish ) they will love the summer production of talapia. This takes a little heat off of the bream , so that the bream will be there for the winter chow line.
I bought mine at Boat-Cycle in Henderson, Texas. While I was waiting in line I talked to some other customers that had driven 5 1/2 hours to come and get these fish for their pond algae problems. One fellow was from Beaumont,Tx and another two were from Oklahoma.
I have heard good things before about the barley hay, there was a good article last year or so in Pond Boss, but it is a little scarce in East Texas as far as I could find. I would be interested if anyone has a source reasonably close to my area though.