[fatman]

As far as the need for live rock. Live rock is principally just a place that supports the prolific growth of nitrifying and to a lesser degree denitrifying bacteria. They are the bacteria that reduce your fishes wastes ammonia to nitrites, then to nitrates and ideally then to gaseous nitrogen that can leave the water. The amount of rock you need is entirely up to the bio load you will place on the bacteria that convert the waste. Fish (especially large fish and predators) create huge bio loads, corals and most invertebrates create small bio loads. You could put huge amounts of live rock in your tank but the bio processing abilities of the rocks bacteria will still only be equal to the normal load placed on them. No bacteria is built up in reserve by having extra rock. The bacteria only develop as much as what their food input allows. IE. to put it simply , if you have only one fish you probably would only need one live rock. If you have many more fish you need many more live rocks. When a tank is initially cycled the bacterial load capability developed is only that needed to remove the load placed on it up to that point. To develop beyond that point the bacteria must be fed gradually increasing amounts of food (organic wastes) their bio load processing capabilities will always grow to the point of being entirely proportional to the amount of food they recieve regularly. If they recieve less food for a while then some of the bacteria die and not as many are reproduced. Saying that a tank needs so many pounds of live rock per gallon of water is akin to saying a tank requires so many watts of light per gallon. Things just do not work that simply. That is why lots of preplanning and research produce the best results with the least amount of waste and mistakes and it lessens the boxes of extra equipment that seems to accumalate with every reefer in the first year or so of reefing.