What could be causing areas of my sand bed to stain a greenish yellow color? I run carbon and rowaphos. I change the media every two weeks. Both media are in its own reactor. I also replace my socks with clean ones every seven days. I noticed it was also growing on the stems of my zoas causing me to lose a few. I have been able to save most of my zoas by dipping in lugols but would like to correct the problem. Has anyone else running gfo ran into something similar?
Parameters:
Dkh 8.4
Calcium 440
Magnesium 1600
Phosphate .04
Could it be gfo dust? I realize my mag is a bit high but I doubt that's what's causing it. Maybe I'm not replacing the gfo often enough and it starts leaching phosphates back into the display? My ro/di top off did reach .01 for a couple weeks before I was able to replace cartridges. Ideas, thoughts, concerns welcome. Thanks