[isaac1]

you could do six million water changes but unless you find the source and cause ur just going to keep feeding the problem, have you been keeping ur lights on for full 12 hrs,is the spectrum of ur bulbs off, do u have a defective skimmer, try reamoving the rocks affected to a qt tank, or take them right out of ur tank and place them in a clean dry bucket for a week this will kill it off, and have you brought water samples to ur local lfs, when in doubt i always go to a store i deal exclusivly with most of the time the staff are extreamly knowledgble and can help better then most posts. hopefully you work it out.