I setup my first marine tank this week. its a 90 gallon overflow tank with sump filter. Just make sure when you buy stuff that you are SURE its what your going to end up using. I ended up buying things for the tank while i was reading the books, and in the end i had to return alot of things to get better stuff, or different stuff because i kept learning different things when i read the books. I also bought cheap stuff cause i was on a tight budget and then had to return it when i used it and realized it was too small or not powerful enough (my heater, powerheads, and return pump were all underpowered for my tank - all cause i wanted to save a bit of money). It doesnt work that way, you have to spend the money on good stuff. I got alot of my stuff off ebay like my sump filter and protein skimmer. Honestly the more you can learn about every detail of marine tanks, the better you are. Learn about fish species and corals and what they need to survive, learn about lighting and the different types of lighting (actinic, daylight, etc) and colors of the spectrum, learn about filtration (sump, wet/dry, trickle, canister, power filters) learn about protein skimmers and why/how/when they work, learn about how all these things work together (like a protein skimmer sits in a sump) - do you want a setup that has everything hidden underneath the cabinet? (has to be a sump or canister) or do you not care about protein skimmers and filters hanging off your tank?) When and if you decide to run a sump filter, learn alot about how they work and what type of plumbing is best for your specific size and dimensions. Also do you want live rock and live sand?, or do you want just fish only with fake ornaments? Just learn as much as possible. My tank has finally come off to a good start after spending almost $3000 on all the proper components and live rock. Its really easy once you have everything set up and going. Also make sure you learn about the cycling process and about beneficial bacteria and learn about test kits too and acceptable levels of ammonia, nitrite, nitrate, phosphate, PH, calcium, etc... you will need to test all these things periodically with a test kit. Theres just so much to learn. I dont know what you already know, but if you know a bit about freshwater tanks then thats a good start. saltwater just has a few more components to the filtration/circulation system (protein skimmer and powerheads) and salt. I started off with a 10 gallon saltwater tank that is now currently my quarantine and hospital tank. It was so easy. I just mixed up the salt water in seperate buckets, ran an aquaclear 20 power filter, small heater, 1 piece of live rock, a few cups of live sand, then the next day I added my first damsel to cycle the tank. make sure you learn about species and cycling the tank. like I said i dont know how much you already know, but i hope all of this helps. The best things to do is read books... one book that I read when i first starting showing interest in marine tanks is "saltwater tanks for dummies" and it gives you the basics and some good info on all the different parts of the hobby. Also try to meet someone at the local fish store who will take the time and talk to you about all the different things you need. I met a guy at the Mississauga Big Al's, his name is Mark and he is the store manager and he spends 1 or 2 hours with me almost twice a week trying to decide what to buy and he teaches me what everything is for and stuff. If your local fish store doesnt know much about saltwater tanks and they are jerks who dont care and sell primarily goldfish (like Big Al's in Brampton, Ontario) then find a better place before you get frustrated. Ok sorry for such a long post, I will shutup now! Hope I helped.