Maybe some type of temporary awning-type structure would provide some shade, at least during mid-day.
This must be an older picture 'cause the water appears fairly clear.
Provide shade; add plants; cut back or temporarily stop feeding the fish and the algae problem will abate as the nutrient levels drop. Be aware that this will not happen overnight and may take some time to show results, but this is the permanent solution. Until then, my friend, plan on continuing to clean the filter pads often.
This should definitely fuel your desire to construct your new pond correctly.
"Everybody is ignorant, only on different subjects." - Will Rogers