Newbie here. I have just a little waterfall pond and won't be getting
string algae. But can you tell me how the straw helps in your larger
ponds and does anything happen to the pond over years Straw is not
degradable is it?

Straw is degradeable.

As it rots, it realeases a small, steady amount of hydrogen peroxide,
which kills algae.

Nothing happens to the pond, other than being fairly algae free.