http://www.reefcentral.com/forums/showthread.php?t=1031074
Read everything there. That is a good place to start. Then read it again and again until you fully grasp it all. After that, if you need any clarification, feel free to ask. Things may have changed since some of those articles were written, and needing clarification is expected. We just can't bottle all that info up into a quick response.
Yes, saltwater tanks require a lot of money and effort, specifically reef tanks (those that contain corals in addition to fish and other invertebrates). Yes they are significantly more difficult to maintain than freshwater, though also significantly more rewarding.
The first thing you have to do is read, read, read. If you don't have the patience or interest to put in the time reading and researching, you won't make it long in this hobby. But if after you've learned more about marine life, water chemistry, lighting, plumbing, electrical, carpentry, etc. than you ever thought you would and you're still interested, you should be on your way to a successful future tank.
I'll provide some quick responses to the specific questions you asked, but I believe you have a lot of info to absorb still.
1. What size tank should I go for? 30, 55, or 75
The 75 would probably be the best place to start. It will have a good amount of water to help keep parameters stable and offers some nice aquascaping options.
2. I am purchasing my tank and supplies on craigslist to save money. Good or bad idea?
Nothing wrong with buying used, but you should know EXACTLY what you want before you hand out any money, and you should know that what you're paying for works as intended. Research all pieces of equipment thoroughly before spending any money.
3. Will I be needing a wet/dry filter, refugium, or both?? Can I get away with just hob filters?
Do some research on sumps for reef tanks. I would not use a wet/dry filter or hob filters at all. A refugium can be incorporated into a sump.
4. Do I need a protein skimmer? Can you recommend one. I have heard some are crap.
This is a debated question but I believe they are well worth the investment. The exact one you choose will depend upon the size tank you go with. Generally, though, you want to avoid Coralife. Companies like Reef Octopus, Vertex, Bubble Magus, Tunze make good skimmers. There are plenty more out there too. Generally if it seems really cheap compared to these brands, it's no good.
5. How long do I need to cycle tank before adding fish and live rock?
Live rock goes in right away. It's the surface on which the bacteria that allow the cycle to happen colonize. Read up on the difference between live rock and base rock and why you might choose to use each. As for fish, it depends on how long your tank takes to cycle. Could be a week, could be a month or more.
6. Mix own salt water or buy it?
Read up on RO/DI units and absolutely plan on buying one, and also a good refractometer, and make your own saltwater.
7. Any special lighting needed for fish or corals? How long lights on/off?
Yes, corals require special lighting. Each coral has a specific lighting requirement. You need to know what kind of corals you plan to keep to decide what lighting will be best for you.
8. What are the necessities?
There are a lot. Good test kits for Ammonia, Nitrite, Nitrate, Calcium, Magnesium, Alkalinity, pH, the tank, the stand, the lights, a skimmer (IMO), an RO/DI, refractometer, powerheads, a return pump if you go with a sump (which I recommend), Live Rock (or base rock, or both), and more.
9. How much will it cost monthly to maintain?
It depends on a lot of factors. Plan to spend lots of money.
10. How much will electrical bill go up?
Significantly.
11. Are saltwater tanks really as hard as people say they are to keep?
Yes. They are a lot of effort, a lot of money, and require a ton of research. As I mentioned, though, they are exceptionally rewarding when you get it right.
