I've just been watching Countryfile and one lass suggested that Water Fleas keep the water free from algaes by eating it
She was on about the Norfolk Broads and how the water has been turned from a terrible condition in the 70's/ 80's to it's very fine condition now, but hey! Do you know any one with a more mature pond as theirs'll likely have water fleas in it & might let you have a jar or two of their pondwater & fleas.
What ever you do next with your pond would you report how it goes & what you think works or doesn't work as it would be really interesting. You're obviously doing so many things right so far, and yes I'd try the stick hoiking method too!
Sorry if I've stated the obvious, just trying to remember what advice my old workmate used to give people for their ponds- he's abit of a font of knowledge
Wish I had a pond to play with too, good luck
