dookie;4820102; said:
first off live rock and fish is a no no. live rock only brings in disease and destruction to a fish tank.
WHAT!!!!!!!!??????????!!!!!!!!!!!!!!!
NO, NO, NO, NO!!!
Live rock is very very beneficial for saltwater fish tanks. It provides a habitat for your fish, it looks good, and most importantly it acts as a natural filter. Every tank should have a good amount of live rock in it.
You should do some reading and make a plan for what you will need to have a 75g saltwater tank. Looking at what kind of fish you want to keep and then posting it here will help before you start buying so that you can get info on what will be compatible.
You will need a test kit and have the tank setup and running for at least a month with no inhabitants so that it can cycle. You will know the tank is cycled when you can test for nitrates and there is a reading. Before that the tank will have to cycle through both ammonia and nitrite which are toxic to fish. This cycle is the same as freshwater really.
As far as equipment goes you will need:
A high quality protein skimmer(most important)(I highly recommend you look at the Aqua C remora)
A filter of some kind like a canister or overflow with sump. The sump would be preferable as it holds equipment, oxygenates the water, and is easier to maintain filter media than a canister.
A couple powerheads for flow. (I recommend 2 Koralia 3's or 4's)
Some live rock(this depends on the look you want. You just don't want to restrict flow throughout the tank)
Keep reading and asking questions and put together a plan and stocklist and then post the whole thing so people can tell you what works and what doesn't. If done right saltwater is very rewarding, I am sure you will enjoy the switch.