It looks like a rush to me. They grow in damp places and plant pots. Lots of them in the woodland garden. Hellish roots to get out if allowed to grow too big.
I agree with @Obelixx. There are plenty of plants to choose from. I have a wildlife pond and wouldn't dream of planting a rush in it mainly for the reason I gave in my last post.
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Wisdom is not putting it in a fruit salad.
Is it some sort of rush? It looks like something that we use to have in our pond (Juncus effusus?).
We are planning a pond ourselves. Do you think I should keep it, or start again with a known plant?