<a href=showthread.php?s=&postid=6793685#post6793685 target=_blank>Originally posted</a> by Dan Fagan
Check your pumps and powerheads in addition to your water params....I had unexplained issues lately until I checked all my pumps and powerheads. In turned out that the smaill powerhead I used to increase flow into my Ca reactor had frozen up and the stainless shaft had rusted! Within a few days of removal, the corals began to color up again and tissue is beginning to grow on the dead spots.
I would have never thoought to check but I read something here regarding rusty screws on Mag pumps that led me to check all the pumps and powerheads...