I started my 150g reef with tap water and prime. the key is a good dechlorinator, prime also does a lot more. I also ran gfo and a good carbon then changed them after 3 weeks. if you use all live rock from a established system or a good store, it also reduces "cycle" I have had no problems setting up tanks this way. I'll be setting one up later today exactly this way and will have fish in it in next couple days.

"Prime® also contains a binder which renders ammonia, nitrite, and nitrate non-toxic. It is very important to understand how those two functions work together. All dechlorinators operate through a chemical process known as reduction. In this process, toxic dissolved chlorine gas (Cl2) is converted into non-toxic chloride ions (Cl-). The reduction process also breaks the bonds between chlorine and nitrogen atoms in the chloramine molecule (NH2Cl), freeing the chlorine atoms and replacing them with hydrogen (H) to create ammonia (NH3)."