Maya
Aquarium Advice FINatic
Hope you now have those fish in another tank cause this one sounds like it is going to cycle again. I'm not sure if you can clean the live rock and not have malachite green and formalin leaching into your tank for some time to come. The meds have killed the beneficial bacteria living in your rock and sand. The general consensus of other sites is to replace your live rock and sand cause this stuff is TOXIC to coral. I don't know what to tell you. You could take a chance, wash the live rock and start over with it, cross your fingers and hope for the best? Or start over with new live rock and sand. One warning though because i don't know how you would CLEAN the rocks... I would NOT boil live rock with formalin in it. Formalin is a pretty well known carcinogen. I strongly advise you against aerosolizing it in your house and then breathing in the fumes.