i gave it a go but didnt think it made a huge difference,afew plants to cover 1/3 of the surface will be just as good.i put a small sheet of wood over a small area just for a few weeks in the begining,only when the sun was really bright,just until the plants grew a bit,otherwise you can buy to many plants and then they take over.
maybe this isnt the usual way but it worked for me,it stops the water going to green all in one go.

ok, thanks for the tip.

we use it and although we get green water when its very sunny we don't get blanket weed-- and barley straw bought as a bale is very cheap in comparison to retail outlets

I thought that it had been removed from retail outlets. It could not be proved to work so the packaging broke the trades description regs. Personally, I think that it is one of these things that does work, just can't be proved scientificaly.

If you wait a few weeks the pond naturally settles as the nutrients run out and the algae dies off.

~Thanks everyone. I'll let nature do her stuff then