scuba, did the outbreak go away at about the same time you switched? I would say that is pretty good explanation for the outbreak going away.
Basically, I have been using tap water. I have a bunch of green and brown algea right now. It doesn't bother me, I kinda like the way it adds color to my tank. Until I get some corals or something that can't live with the algea, why should I switch? That is what I am trying to figure out.