Saltwater fish tanks

This is going to be kind of long, so let me apologize now.....
I know very little about using live rock as a bio filter, or reef tanks. My only experience with them was the little one I had, and I got it as running fish tank from the store I dealt with. But Reef Central is the forum to go to for info on reef tanks....more on my little set up later.
First thing you need, beyond the basic knowledge of how the nitrogen cycle works and the necessary kits to see that the cycle is happening is good water. My tanks were all started with just good old city tap water and they cycled with no issues but ro water is a much better bet. RO water will have a tds of close to 0, which for one will mean the water has no impurities in it. So the water will be clear, and have nothing in it that might harm your fish/coral. I used a Spectrapure RO/DI unit. With RO units one thing to be concerned about is the rejection rate. Good units, when the water temp/pressure is adjusted for, will have about a 3-1 ratio. For every 3 gallons of water thru the RO you have one gallon of "good" water, if I remember correct. Scott, the Spectrapure guy, is a great guy to deal with. His site has some info under the faq section that explains a bit about RO units.
My little set up worked very well. I do not know how it would have survived in the long term as I only had it for a year or so. It had some live rock in it, which acted as the biological filter and then it had a hang on the back mechanical filter. There are several things that turned me off of using live rock in my big tank, one of them being the smell. The live rock has to cycle with your tank. And it will stink, badly. When I used to walk in my friends store I could always tell when he had some fresh live rock.....from the parking lot. More later....