I've recently purchased a property with a pond. There is large amount of algae, producing a scum like film on the surface. I've found chemicals that are safe for the fish (blue gill, bass, and catfish are present) that you can apply, but have also found other options such as raking or planting water lilies. I have yet to try anything, looking for a starting point and most importantly I don't want to harm the fish. Also, considering an aerator.
What are you calling algae ? From the question , it sounds like you don't have a background in ponds. Books or internet are good. There are many floating plants but in many ponds I have seen, I never saw floating algae scum. Green water a couple times ; even had it a few days myself long ago. Generally the chemicals are to make money for shops or for swimming pools. Many fish nibble plants, Koi and catfish downright eat them ; so if you use algaecide, you will likely kill or injure fish. If I had macro-algae in a pond , I would add plants and try to determine the source of nutrients. Higher plants will out compete the algae for nutrients and starve it. Water lilies are good but I think floating plants will get nutrients faster. I have duckweed, water sprite, hornwort, anacharis , water lilies, but there are a great many . Some may be illegal in your location , but things like water lettuce, and hyacinth are easy to pull out of the pond after they soak up nutrients and multiply.