If you read my thread about my sick colt coral, you might remember me mentioning that the LFS tests revealed that my nitrates were super high...80+. I did a 21-gallon water change (~180 g setup with fuge and sump) and added two bags of a compound called DeNitrate. That was one week ago. I had my water retested at the fish store last night and my nitrates were 10. The colt still looks rather puny, but now that I'm getting my nitrates back under control, perhaps it will come around. I just finished a 14 gallon water change.