I'll be a little more direct than Ben.

Don't use copper to keep algae away.

A better and more compatible algaecide is called PolyQuat. It's called Black Algae, Mustard Algae or just algaecide. But the key is the SOLE active ingredient is 60% Poly......<something long and unpronounceable>.... If you add about 1-2 ounces a week, if your FC falls a bit low it will inhibit algae. But it's better to keep your FC up to the maintenance levels suggested by the "Best Guess Chlorine Chart" (see Ben's sig for the link). Copper turns blond hair green and stains pools.

Carl