water quality problems
 

I recently had an Aquascape Pondless Waterfall installed and I love
it. However, I am overwhelmed with all of the "products" offered for
upkeep. My present problem is algea that is forming on the rocks along
with what appears to be a brown stain on rock surfaces. I do not yet
have fish or water plants. I also have a leak somewhere in the liner
and have to top off the water every 2-3 days--could "tap water" be a
contributor to the problem. Thanks in advance for any assistance.