A few million SW n00b questions

[Corn-Picker]

Hi everyone. I got a 29 gallon tank for Christmas and I'm ready to give saltwater a try. I've found a lot of useful info on the site, but there are a few things I still do not understand.

What is liverock? Is this the same as coral, different than coral?

Is liverock necessary for a SW tank? Does the liverock do any filtering or does the sand bed do all of the filtering?

If I do get liverock, what kind of lighting is necessary? Is the light that came with the tank (a cheap one) good enough for liverock? The cheaper light is fine for the fish right?

Is lighting as simple as getting a replacement bulb, or, due to increased power demand, do I need an entire new light fixture?

How deep do I want my sand bed? 3 to 4" seems to be an answer I've run across a lot.

Also, what should be the composition of my sand bed. I live in the Northeast, so getting the good Southdown sand shouldn't be a problem. Is 100% Southdown sand good, or do I need to throw in "live sand" also?

My tank came with a filter (the kind that hangs on the back and takes charcoal cartridges), do I need to invest in a new filter?

What kind of protein skimmer should I invest in?

Do I need water pumps to circulate water if I have live rock?

How many inches of fish are too much fish for a 29 gallon tank? I was planning on 2 clown fish, maybe 3-5 lemon gobys, and a fairy basslet; is that going to be too many fish for my size tank?

Thanks for any help you can provide.

[OrionGirl]

Live rock is porous rock that has beneficial bacteria living on it, along with other animals, like sponges, algaes, worms, etc. It is not the same as a coral. A coral is an animal.

While tanks can run without LR the benefits of having it are enormous. It will provide the vast majority of your biological filtration, as well as providing cover and shelter for your fish.

NO lighting will work for LR. There will be some die off of photosynthetic creatures, but the bacteria don't care about lighting levels. Ditto for the fish.

Upgrading lighting requires more than just a better bulb. There are a variety of NO (Normal Output) bulbs you can get, but for more watts, a better ballast is needed.

Sand = 3-4 inches is great. You can use all play sand, or mix in some live sand, or just add an activator kit (much better, IMO).

I would run the filter without any media to help provide current only. Some powerheads will also be a good item to add, so you can provide for even current distribution around the tank, and avoid dead spots.

I would go with the clowns-percula or ocellaris, not maroons or tomatoes, and maybe 2 other fish. The carrying capacity of SW is much less than of FW. 3-4 small fish will be fine--much more, and you will have problems.

You may want to pick up a good book. Look into fishless cycling!