I have inherited a pond, when moving home. I have just cleaned it all out and put the fish back in (around 200 goldfish, orfe and others). putting some more oxygenating plants on, but someone mentioned putting trees in the pond, in pots. I have a weeping willow, 7ft high, that's been in a pot for some time. Does anything think its safe to put in the pond on a shallow shelf. If so what other trees are suitable for this....