I would try a clarifier such as this...Its what I use.

http://www.lesliespool.com/leslies-u...tra-bright.htm


And as far as the metals in the pool that you may possibly have I assume the blue or pink stuff here.. Ones more aggresive for iron ( Pink) And ones more aggresive for copper ( blue)

http://www.jacksmagic.com/our_stuff_..._cleaners.html