Whats going on people, im new to owning a saltwater tank i just recently set up a 55g with two blue damsels and a 3 stripe damsle, and a engineer goby, and a osc. clown. and a choc. starfish... but anyways the tank was running for two weeks with 5 lbs of live rock before i added any fish, but three weeks after stocking it i noticed some sort of brown stringy alge growing on the glass and rocks. all the params seem fine except for the water being really hard. what would cuase that? and how do i get rid of it?