FM, as I said before I am no expert, but CC and tap water are not real favorites on this board. You can do a search and find many posts about people changing from CC to LS. Also all tap water has "stuff" in it that is not good for your tank. You should be able to buy some RO water from any gorcery store that would be better for your tank.
One other thing if I may (I don't want to sound like I am preaching to you) that is a lot of stuff to have in a new tank. You had a pretty heavy bio-load in your tank and the new rock just pushed it over the edge. One thing that is often said in this hobby is patience. You need to let your tank build up all of the good bugs and bateria before you add something else.
I think now would be a good time to switch from CC to LS and then add to your tank slowly.
Like I said I don't want to sound preachy to you, just trying to help you out.
Scott