Which color of algae was floating up?

Algae feeds on nutrients in the water. It can't compete with vascular
plants. What other plants have you in the pond?

Have you a veggie filter (small pond with lots of plants to grab
nutrients and to filter muck out of the water).

If you have vascular plants, they will gradually clear the water by
grabbing nutrients.

A UV will help as well if you have one. It comes into its own with
the green water. The UV will screw up the DNA and the green water
will go away.

Good luck