I recently had the same issue with my new pond. What I ended up resorting to was weedblocker. I cut up small shapes and lay them on the surface of the water, around the pads, leaving windows for the tubers to get sunlight, but about 80% of the surface is covered with either pads or weedblocker. It's the only thing I could think of to block the sun without adding any chemicals. It floats regardless of whether it's partially submerged or not, and it's light weight enough that if a pad/bloom needs to move it, it can. It's working, along with more aeration, ClearZyme, and Accuclear. NO ALGEAFIX. It's useless. I am able to remove it daily as the sun goes down, but that may not be practical for everyone. In the morning before the sun hits the pond, I start putting it back. It's different everyday, since the pads move, and more are on the surface. I am using smaller and smaller pieces daily. I have batting in my filter, and wash it out every other day. May as well try it, if it's doable.
Just to be clear, I do NOT cover the pads. If some blocker gets under them, there is still a layer of water between the pad and the blocker.