Question: We have a large pond prone to duckweed. We have tried scooping it out and additions such as barley straw, but have had no luck getting rid of it. Do you have any suggestions?
Answer: Duckweed really is a difficult one. Continuous scooping out is the main control - barley straw extract can help more with algae suspended in water. If you can get waterlilies or other plants with floating leaves, established to shade the pond, this may help.
You could shade the pool by planting on the south side and if there is an inlet to the pond, install stop boards upstream. Persistence may well be the name of the game here, with a mixture of getting the shading right and keeping going with the constant removal of this determined water weed.