Hello tamuchick02 and
I want a 20 gal tank, saltwater reef type, some coral, quite a few inverts, and some fish. I need your help on brands and sizes of equipment, what equipment I actually need, the best place to go and get them, types of livestock and the best places to go and get them.
First off I'd point you to our newbie guide if you haven't read it already:
http://www.reefs.org/library/newbieguide.htm Have you decided if you want a glass tank or acrylic? All-Glass amonst others make nice glass tanks.
From there, I would recommend you read thru
http://reefs.org/library/reading/ in the respective sections of creatures you'd like to keep. Write down the stuff you'd like to keep and then check for compatibility with each of the creatures and to see if they'd do well in a 20 gal tank. If I had to recommend 2 books to reference, I'd say read:
Marine Fishes : 500+ Essential-To-Know Aquarium Species (The Pocketexpert Guide Series for Aquarists and Underwater Naturalists)
by Scott W. Michael
Publisher: Microcosm Limited; ISBN: 1890087386; (November 1999), 448 pages
and
Aquarium Corals : Selection, Husbandry, and Natural History
by Eric H. Borneman
Microcosm Limited; ISBN: 1890087475; (March 2001), 464 pages
Once you know what fish and coral you'd like to keep and have checked their compatibilities with one another, then continue designing your system. The biggest thing to decide then is your lighting as the corals you select will ultimately dictate your lighting scheme. Soft corals (mushrooms, zoanthids, etc) don't need as much light as hard corals (hydnophora, acropora, etc).
After that you'll need to decide what skimmer to get. Personally I'd recommend either the PM HOT1 hangon skimmer or the AquaC Remora or maybe the BakPak but I've had peronal problems w/ my BakPak so I'd recommend the first two skimmers first.
For a 20 gal tank I'd probably recommend a 2" to 3" deep sandbed comprised of either CaribSea Sugar Sized aragonite or else use Southdown playsand. Southdown playsand is much cheaper, but it's somewhat hard to find depending on where you live in the country.
Liverock can be purchased from any of our sponsors (link at the top of the page). My personal preference is Harbor Aquatics as I've been impressed with the amount of life on their rock. Hardware can be purchased from any number of our sponsors.
Sorry to be so long winded. I hope all of this helps and welcome to our community!
Shane