You are probably referring to filamentous algae.
I'm sure there are a wealth of reasonable chemical solution, which are completely valid, but you might want to diagnose why your pond is covered in the stuff and work to lessen those causal factors.
For example, do you have a lot of agricultural runoff? Fertilizers washing into your pond, could create large algae blooms. To improve the situation, you could add a 100 foot buffer zone around the pond with terrestrial vegetation that will help to filter the runoff. You could also consider lower impact ag practices, like no till farming. Finally, you could make sure that your pond has a healthy population of other aquatic vegetation, like cattails, arrowhead, etc. These other aquatics will sequester nutrients and limit the growth of the algae.