[Goosegirl]

Having Giggled various ones, can anyone recommend a good one for a small pond?

[LotuSeed]

A fine mesh net with a handle. I think I got mine when I was at the beach one year. I have duckweed in my pond too. I find the net works well, is easy to use, and doesn't harm the other plants and organisms living there. You could put water hyacinth in, which would eventually crowd it out, but then you'd be asking how to get rid of that too. Multiplies like crazy.

[8doubles]

Best duckweed killer is a duck !

If you have other pond close by it is near impossible to get rid of duckweed as a frog will bring fresh stocks on its back when it pays a visit.
A small mesh net as mentioned or you can sometimes overfill the pond and float it off.
Taddies will eat the roots  when they get hungry enough!