Strange event in garden pond

Asa Post

Small lungs, weak legs
Location
Sheffield
This morning I walked up the garden and saw this:


IMG_20190814_105830830.jpg


The floating plant is duckweed. It usually covers pretty much the entire water surface. The small circle is the feeding ring for the fish. Once weed gets in it, it can't get out until I pick the ring up and clean it.

But what could have caused the big circle? There's nothing at the edge of it to keep the weed together.

There's a pump/filter/fountain in the middle of the pond, but I don't see how it can push the weed into this shape and keep it there. I've had a pump for years and this has never happened before. It still looks the same 12 hours later.

Any ideas?
 

classic33

Legendary Member
Any water movement in the pond?
 
Location
Loch side.
It seems as if you have a grid or net over the pond. Correct? If so, it seems flexible. Correct? Then, something caused it to sag in the middle and touch the water in a perfect circle. The duckweed then gets trapped in that submerged section and you have a green dot. That's my guess.
 

postman

Legendary Member
Location
Meanwood ,Leeds
The wind creates an eddy, sending the weed into a slow spin.


Like this Eddy you mean.

View: https://youtu.be/fTN2bvVCOQs
 
OP
Asa Post

Asa Post

Small lungs, weak legs
Location
Sheffield
It seems as if you have a grid or net over the pond. Correct? If so, it seems flexible. Correct? Then, something caused it to sag in the middle and touch the water in a perfect circle. The duckweed then gets trapped in that submerged section and you have a green dot. That's my guess.
Yes to the flexible net, but it's stretched tight and pegged down, so it doesn't touch the water at all.

The wind creates an eddy, sending the weed into a slow spin.
I wondered about that, but the circle of weed wasn't rotating. It was perfectly still.

Your goldfish are bored and they've read about naughty Agriculture College students who go out in summer and make crop circles.
I like this. :okay:
I'll assume it's the correct solution until somebody proves otherwise.
 
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