I think you may be right. I thought I had turned it around. I did several water changes and began running carbon religiously again and things started to improve but my phosphates started to rise so I started using phosgaurd mixed in with my carbon and it seems to be happening again. The only other thing I has done is dose nitrate to get them to a detectable level. They are currently at .5 I took the Phosgaurd out and am going to mix a small amount of GFO into my carbon to help keep phosphates in check and see if that helps. At this point I think it is either the phosgaurd or the nitrate dosing although I'm not sure how the nitrate dosing would cause while spots, I would think it would cause algae which it hasn't.