Coral Killer

Yeah, but let's see if I can get rid of it.
From what I've read, some say I need to start from scratch and some think it won't be problem after water changes and carbon/poly filter.

 

This is just my 2 cents worth... but before I started my reef tank over a year ago, I had a fish disease (crypto) those white spots ??? Anyway, I used Copper to get rid of it and it did cure my last 2 fishes.

I then started a series of water changes to try to get rid of the copper and tried for 2 months changing 5-10 Gal a week and the copper just would not go below 1.0.

After 2 months of this frustrating changes with no copper change, I gave up, and re-built the tank from fresh.

I don't know how long it would take to get rid of the copper, but I would suggest to start from scratch and use your fish as initial stock to condition the tank.

 

Heavy carbon use to pull the copper out helped me when I inherited a used "reef " setup. i changed the carbon once a week for two months and it pulled the copper out saving me from tearing the tank down a second time. watch your snails and hermit crabs if you have any. They don't tolerate copper and will die off also. What did you change the fitting to?

 

I thought the same (metal poisoning). Observe if any invertebrate/worms/feather dusters is alive on your rock.
Something metals are deadly enough to corals but still not toxic to fishes is in your tank. if the rock worms are dead then it could be metallic in nature.

good luck on your dilemma.