Well Toadletfan I never knew that about watercress! Fortunately I threw a bit of watercress from a salad I was eating into our pond years ago and it's grown there ever since

We do get some blanket weed but not right across the pond. Maybe the watercress is doing the job on it's own but we also put a 'magnet' on our filter as well years ago so it might be a mixture of things that we have tried.

We get blanket weed on the water feature and on the filter top but nowhere else so we can just about cope with that. It is a pain though when you get it all over the place. I hate taking it out because all the little creatures get caught up in it. I leave it on the edge of the pond for a day before lobbing it onto our compost heap to give them a chance to get back in the pond.