Hey all,

I recently moved into a house and it has a lovely little pond about 1 metre by 1.5 metres. It's currently teaming with tadpoles and has 3 or 4 good size frogs.

I've been wondering what the green algae looking substance is onto of my pond. I know think it's Duckweed. I've been reading on the Internet and it seems as though it has many benfits for the pond, so I just need to keep in under control. The problem is that I clean 80% of it out of the pond and within two days the whole water is covered again.

The pond is located under a Maple tree so has at least 2 winters worth of leaves in he bottom. Is this rapid growth associated with so many nitrates in the water?

Cheers,
Nick