Shade your water feature
Algae love stagnant water with much sunshine. Just like any other plant, they require sunlight to perform photosynthesis. In fact, almost half of the world’s photosynthesis processes come from algae. If you can move our fountain easily, then place it in a shady area. You could also plant other vegetation that will grow and cast a shade on the water feature. These plants might include lattice, bamboo peach trees.