enayba,

Your post is exactly why I started this thread. There aren't any easy answers for eliminating duckweed and its close relatives.

Thankfully, I've never personally had to try and eliminate duckweed. However, it doesn't mean I haven't had a lot of issues with duckweed.

I power-washed my aunt's dog after he jumped into a pond covered with duckweed. I didn't let him into my watershed for about two weeks after that adventure.

Aereation would certainly help. The oxygenation from the diffusers would help stir up and eliminate some of the excess nutrients that let duckweed and other water plants flourish.

Chemicals will help kill the duckweed and other vegetation, but the amount of chemicals you will need, could easily contribute to the decomposition of lots of dying weeds. They will take up a lot of oxygen, which may kill many of your fish due to lack of oxygen from the dying plants.

Probably the closest I've come to controlling it, and many other unwanted pond growths, has been cleansing excessive nutrient water inflow.

That obviously is not always easy or possible.

At one horse farm site we cleared the water by landscaping. We moved a lot of dirt to divert runoff from pasture/paddock/riding rings from flowing into the ponds. We dug a trench to bring clean water into the ponds from a creek above the horses. We ran 8-inch PVC pipe. That water is piped into a settlement pond ahead of the main pond. The settlement pond is actually a koi pond with lots of vegetation that takes up nutrients. Its water feeds two other ponds that include grass carp.

It all works. Unfortunately, every situation is different.

Don't give up,
Ken

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