Thanks, Greg. This is definately DINO.(that was the name I was looking for) I've had Cyano before, and won that battle, but this garb. is real fight. I am not sure what else to try. Have a great skimmer, syphon almost bi-daily, numerous water changes, carbon use, calcium, cut back on feeding, no addatives. I can try and increase the flow across the sand, althougfh I can't imagine adding anymore power usage to this tank without blowing breakers

. I don't know how much cutting back on lighting really helps, but I guess that is another area I should investigate.
Anyone else have experience with this stuff?
Harpo