When I first set up my tank, I was using RO, then I got chatting to a really nice elderly guy in my local fish store, and he told me that he has never used anything BUT tap water for the 40 odd years that he has kept marine fish. He told me this when I went in to buy an RO top up. Further to this he showed me pictures of his tanks, they looked phenomenal with fish, corals, anemones, and live rock. I asked him what he put in his tap water, and he said "absolutley nothing" straight out of the tap, at the right heat and salt content, perfect.
His argument was, that what did folk do to keep marine fish before RO came on the scene?
I changed to tap water immediately, and can I say that I have NEVER had any problems whatsoever. I have added fish that I have bought from the fish store and they are very happy, and I have had one in particular for 2 years, a Blue Trigger. NONE have ever died in my tank of tap water.
So there ya go!!
Sorry, can I add that i am in the UK, and not SF as I have just noticed the thread is concerning.