Although I'm farther south than Rod, here are my thoughts.
Tilapia are a restricted option in NY, but not having predators big enough to eat them in the fall creates another problem, which is a pond covered with dead tilapia. A rake works, but it is labor intensive. I have a 12' handled driveway rake, and pull algae up on the bank and let it dry out. When dry, it's very light, and easy to remove. We put it in our compost pile.
A possible treatment option might be Greenclear Pro. It's a non-copper algae treatment, and according to a NY state report, "there is no significant threat to
the environment, the populations of organisms residing therein, or public health and safety". This may be an option. Just for clarity, I haven't used Greenclear yet, but I'm using it for algae control in a pond that irrigates an elderberry orchard. I wasn't comfortable using a cooper product for a FDA approved food test.
NY State Report
