What do I do if it's my rock leaching the phosphates?One thing I would point out is that, IMO, a 3 day black out should be a last resort to resolve a major issue with problematic algae. I have done it and it can stress out SPS, causing them to lose a bit of color. Yes, the color will typically return but a frag that is in a weekend state can die. I also once lost a Black and White Maxima clam. As others have said, the source of the problem has to be fixed or eventually the algae will return. So finding the source and fixing it IN CONJUNCTION with a 3 black out can be very effective.