So glad to hear you've been wondering about this too! The fountain broke about three weeks ago now; we informed the estate office right away, but they said it was a not a priority as it is largely cosmetic. We did point out that it covers noise for flats in the immediate vicinity, which now have a much increased number of people coming through to use the green spaces; but, more importantly, that the pond is an ecosystem -- re. the plants as well as the large number of fish that live in it. As you've mentioned, there is now a scum on the pond and the water is no longer clear, but murky green. I'm not an expert either, but I don't think this is good....that's why there is a pump in the pond in the first place. It would be terrible if the fish died. I'm not sure of the status of any repairs underway, but if you (and any others) want to write to or call the Estate Office to reinforce these important points already raised, it might help!