Duck weed.

I am asking for friends. They have a pond about 30ftx15ft approx. There are no fish in it atm as a Heron and Osprey demolished the showel of Coy Carp some years back.I think the pond was netted but still the lot was scoffed.
They want to get the pond back into shape and have just redone a very attractive waterfall over a mound of big boulders which looks lovely.
Big problem is the duckweed which is literally covering the whole of the surface of the pond. I believe this starves the pond water of oxygen? and as such would not be good if friends restocked the pond.
They have used nets to remove as much of the weed as they can but it just comes back again.
Any ideas as to how to get rid of the stuff? It would need to be non toxic to cats as friends have quite a few and they drink out of the pond. Hope someone has a good remedy.Thanks.

 

Don't have a remedy other than my pond gets covered in it every spring, it then slowly dies back as the oxygenating plants get going.

I always find the water is crystal clear under duckweed, mine has gone green since it's all gone.
My goldfish always survive well enough under it, the waterfall will add lots of oxygen.

To cut down on it I spray the surface with a hose and push it all up one end then scoop it out.

 

Thanks Pete, the idea of hosing the weed to one end sounds a good one. I will pass that on. I agree the waterfall should add a good amount of oxygen to aid new fish if they decide to restock. How to tackle the winged visitors might be a bit more tricky! Perhaps the net was not fully covering the pond and allowed restricted access. I know friend actually saw an Osprey with one of their Carp in it’s claws being swiftly removed over the hill!

 

Never seen an osprey, we don't get many of them down here .

But the net needs to be above the water, personally I think nets look awful .
I have pots with tallish plants around my pond, it's a deterrent but seems to work in the summer months for herons, in the winter stretch ropes across the pond or lay like bean poles across it.
Any thing that is unstable and moves if they try to land on it.

 

We are talking about Lemna, yes? Any members of the carp family feed on it, so if your friends are going for Koi or goldfish, it'll be a food source for them.
Visually, perhaps bamboo sticks and transparent line, e.g. strimmer line, criss-crossed over the pond would be less obvious than a net. The disadvantage of that is the possibility of the birds getting caught up in it.

 

Are you suggesting my duck weed disappears in the summer because the fish eat it?
I hadn't thought of that.

 

Thanks Noisette. I think my pals are planning to restock but perhaps with less expensive fish just in case they attract unwanted visitors. They do not want to repeat being a carry out again, literally. I will pass on the info as I think they mentioned getting gold fish rather than Koi. Can you still get a gold fish in a wee poly bag at fairs if,you as an example, hit the bulls eye? It has been many many years since I visited a fair.