[DEAD_BY_DAWN]

i think from the fact that you have any ammonia in your tank,and i would assume some nitrite that there is a cycle going on,the best thing you can do is remove all fish and inverts till it is finished,then slowly start putting them back in,i have personaly found that doing as you said massive water changes can cause more harm than good if you are shifting from one extreme to another,testing you cal level is not super important at this point ether from what you have listed for corals etc,you dont seem to have any stony corals so i would take a guess and say that you cal level will be high,and finally for the cyano covering your tank this should dissaper when things return to normal ie low nutirents if not them chemi clean will kick its ass within twenty four hours..good luck things should work out fine with a little bit more time ..john