I am not aware of copper preventing algae. But in aquaiums you use copper to rid certain infections in salt water. But I do know if you get to much copper in the water it will kill all the invertibrates in that tank. But the fish will be fine. I dont know what it would do to vertibrates but I would not want to try it to find out.One last point I would like to make is the highest percentage of a penny is zinc. I know this isnt what you were looking for but I hope it helps point you in the right direction.

mtnsnakeman@excite.com