As some have suggested, sail shades will make a huge difference, but you might also want to consider adding plants as well. They’ll provide some shade and use up some of the nutrients that the algae need to grow and survive.

It also would don’t hurt to throw in a barley straw bale as well: https://smile.amazon.com/dp/B0002568YK/ref=cm_sw_r_cp_api_glt_fabc_HP37RN5Z11N1C6KSTHH3

These are made for 1000 gallon ponds, so what I did is cut open one end, pull out a good portion of the straw and stash it in a ziplock bag, and then tie off the open end.