My pond is losing water

Urgent, lives at stake, fish lives at stake.
My best mates have gone away to America for two weeks and have paid me to go round to their house and water the plants until they come back.

I've been watering the plants for about 3 days and when I went to their garden I noticed the fish pond had drained to an alarmingly low level.

It is one of the ponds with that black lining and has a filter in the form of a little fountain.

The fountain is a little blocked but the pipes don't' leave the water so i don't know how it is losing water.

Help!
Answer:
The little holes in the fountain head got blocked, but one or two remained open and the water just spurted out of the pond. Open the holes on the fountain head with a tooth pick OR just remove the top until your friends get home. Refill the pond and don't forget the dechlor.

f your pond is concrete, liner, anything but a natural bottom, you could use chlorine to clean it.  That will kill the duckweed. Then you could add extra dechlor when you refill.

To find more pond information, go to pondlady.com