The algae forming on the rocks is natural and usually considered to be healthy
for a pond. As long as it doesn't completely obscure the rocks I'd leave it
alone.
The addition of new water does help it along as fresh water is one of the food
stuffs for algae growth. And there are forms of algae that are brown, but it
might also be some kind of mineral stain. Probably depends on your water
source.

If you had it installed and if it leaks then you should call the installer. But
also take into consideration the current weather conditions. Air temperature
and wind can cause water to evaporate.


kathy :-)
algae primer
http://hometown.aol.com/ka30p/myhomepage/garden.html