The value of cured live rock comes from its role in a saltwater reef aquarium where the reef is the major filtration system. First, the bacteria and algae on the rock remove chemical compounds containing nitrogen and phosphorus, which can be toxic to animals, and the algae consume carbon dioxide and produce oxygen, all of which are advantageous to aquarium animals. If the reef is populated with brightly colored corals, the filtration effect is vastly increased. In return, the photosynthetic process in the zoozanthellae consume carbon dioxide and release oxygen, both beneficial to the corals, and produce sugars, which may be an energy source for the coral host. Zooxanthellae have a major benefit to stony corals by promoting the deposition of calcium carbonate, the backbone of the coral reef.
Coral reefs grow only in shallow water and grow faster in sunlight.
Beginning saltwater aquarists often are not prepared for the costs of a reef system. After getting the necessary equipment - lights, pumps, skimmers, heaters, coolers, etc. The uncured rock would pollute the system, causing all kinds of changes in water condition, increase the level of pollutants, and seriously damage some of the less hardy species in your system. If you buy from a catalog or e-tailer, you, the buyer must beware. Here are some things to look for in a bad deal.