People telling you what you need and yet you haven't said what you want.
2 basic saltwater setups: Fish Only With Live Rock (FOWLR
Reef ( corals and fish)
Then there is also predator tanks with cool but agressive fish (eg. Lionfish) but that don't play nice with corals ( unless eating corals is nice).
Once you've decided that, then you can begin the road to equipment.
sterilizers are definately NOT a requirement. Personally, I don't have one and have strong opinions on this. Many others don't either, but then again many others do.
The biggest equipment decision on equipment I believe to be the addition of a sump. It can do cosmetic things like moving other equipment out of the display tank (DT) as well as house more rocks. But the most important thing (other than a skimmer, but that is covered in equipment) is the addition of chaeto into the sump. Fish won't eat it there and it will consume nitrates and even phosphates.
Here is a link to the getting started articles that doesn't show up on the phone.
We have a series of articles to help get you started
Good luck. Keep asking