Thank you for all of the information and good ideas! I thought about
finishing the concrete, but have heard too many stories about concrete
cracking and leaking - I'm north of San Francisco and the ground
doesn't freeze, but we have a lot of rain and the ground gets
saturated. I don't want to use chlorine- I would like it to be
attractive to birds. A friend has a concrete drill and we are going to
use a strip of aluminum or maybe copper that will be bolted through
the liner and underlayment to the brick. I love the idea of a
waterfall or spitter and it sounds like a pump to keep the water
moving will be all I need unless there's an algae problem - I'll start
reading about barley pellets and other algae treatments. Thank you
again for the help!