First off, I'd question your decision to only keep fish only with live rock (FOWLR). Make sure this is what you really want by visiting local saltwater aquarium stores so you don't buy the wrong equipment. I started this hobby by only wanting a FOWLR tank...and now I keep really hard-to-keep corals. You don't want to have to upgrade equipment anytime soon.
Our sponsors are Aquarium's Etc, Just Coral (by appointment only), and North Dixie Reef. These are excellent places to start researching different systems and livestock.
If you're set on a FOWLR tank, in my opinion, the two best filter systems are the Wet/Dry filter and the Refugium/Sump. The Wet/Dry will probably cost you most money initially unless you find one used. It will require some plumbing, but it's not too hard. The only other downside to these systems is that they're not easily upgradable in case you decide you want to keep corals later down the road. A Refugium/Sump is basically a second tank connected to your main tank. This tank serves many functions, like holding extra water (the solution to pollution is dilution!), keeping unsightly macroalgae to use nutrients so that algae will not grow in the main tank so much, and to hold other equipment. Usually most sumps contain extra live rock to act as a filter.
If you're doing a FOWLR tank, don't skimp...get a good skimmer. This is a huge initial cost, but you'll probably regret it if you don't. You can get some good used ones on here, our sponsors, ReefCentral.com, or at the local swaps.
With a FOWLR tank, lights may or may not be an issue. Many people just run normal flourescent lights (shop lights) over their aquariums, but other people like the *shimmer* that metal halide lights give off. With LED's you can obtain the same *shimmer* with a low electric bill...but it would take a lot of LED's. Many people just supplement flourescents with LED's. If you're going to keep corals, you'll want to step up to the Power Compacts (PC), T-5's, or Metal Halides. All have their pros and cons, which I won't discuss yet.
For a FOWLR tank, you won't have to worry too much about flow, but you'll still need to add some powerheads for extra flow.
Ok, here's my order of things to do:
1. Be patient
2. Do lots of research on finding exactly what you want to keep/compatibility
3. Get the tank and stand (make sure the doors are plenty big on the stand to do maintenance. If you can't reach all areas under the stand, you probably won't do maintenance as much as you should.)
4. Get the filter
5. Get the skimmer (make sure it's compatible with your filter...plumbing and all.)
6. Get the powerheads
7. Get a hydrometer/refractometer (something that measures the salinity of your water), an Ammonia/Nitrite/Nitrate/PH test kit, a thermometer, salt (Instant Ocean is a good inexpensive brand), and filtered water (you can buy reverse osmosis - deionized water at local aquarium stores...which is what you should use).
8. Test fill your aquarium system to check for leaks
9. Get your live rock (LR) and sand. You'll want 1.5-2lbs of live rock per gallon of water in your system plus another pound of sand per gallon.
10. Make saltwater out of the purified water and salt. Use the hydrometer/refractometer to measure the salinity. The salinity should be around 1.025 (which may differ depending on your inhabitants.)
11. Put your powerheads and skimmer into your saltwater (this can be done in your tank or in a large rubbermaid tub...whichever.)
12. Place your live rock and sand into the water, turn on the skimmer and powerheads. This is cycling your live rock to get the nitrogen cycle going. Bacteria will establish itself at this time.
13. Check the chemical levels about once a week while the rocks cycle.
14. Until the levels read: Ammonia-0, Nitrite-0, and low Nitrate, perform weekly 10% water changes with the saltwater you made.
15. Once the levels are on target, you can move everything into your tank...or if you did this in your tank, you can add the lights.
16. Don't add anything to your system until you start to see algae growing. Keep testing chemical levels weekly.
17. Once algae starts growing, you can SLOWLY start to add a clean-up crew (which may consist of blue or red-legged hermit crabs and warmer-water snails.) Avoid specialty crabs, snails, or starfish at this time.
18. Once the algae seems to be in check and the levels are stable, you can add ONE fish. Take this slow. You don't want to crash your system by adding 30 fish at once. It's best to place your most shy fish in first so it can get established.
19. Once the levels stablize, you can add another fish. If nitrate levels start rising, you'll need to either quit adding fish, or cut back on feeding. Many invertabrates and fish cannot tolerate high nitrate levels (plus it fuels algae.)
Ok, that should start you off pretty well. If this sounds really complicated, I'm sorry. I've made my mistakes and watched a lot of other people make mistakes. There are easier ways (and cheaper) to do this, but you won't be happy most likely.
Any questions?
Nikki