We have a man made dug out pond, large with gold fish, frogs, all the little critters you can think of and when we get the algae and scum come to the surface in the spring after the ice thaws we rake it out, some sinks back, it doesn't seem to hinder te fish and other creatures. If your's is an artificial plastic pond, just scoop out the algae, throw in some oxygen producing plants and some fish, but don't use duck weed.
