The oxidation reduction potential (ORP) of marine aquaria is a measure of the relative oxidizing power of the water. It has often been recommended to aquarists as an important water parameter, and some companies sell products (equipment and chemicals) designed to control ORP. Many who recommended ORP control have convinced aquarists that it is a measure of the relative "purity" of aquarium water, despite the fact that this has not been clearly demonstrated.
ORP, at its heart, is very, very complicated. It is, perhaps, the single most complicated chemical feature of marine aquaria that aquarists will typically encounter. It is not hard just for aquarists who are not scientists. I had to learn a great deal about the electrochemistry of natural waters in order to write this article, and had help from a number of other chemists in understanding some of the principles that are usually swept under the rug. ORP involves many chemical details that are simply unknown, either for seawater or for aquaria. It involves processes that are not at equilibrium, and so are difficult to understand and predict. Even more daunting is the fact that the chemical species that control ORP in one aquarium might not even be the same chemicals that control ORP in another aquarium, or in natural seawater.
Guys the rest of the article can be found here:
http://www.reefkeeping.com/issues/2003-12/rhf/feature/index.php
ORP, at its heart, is very, very complicated. It is, perhaps, the single most complicated chemical feature of marine aquaria that aquarists will typically encounter. It is not hard just for aquarists who are not scientists. I had to learn a great deal about the electrochemistry of natural waters in order to write this article, and had help from a number of other chemists in understanding some of the principles that are usually swept under the rug. ORP involves many chemical details that are simply unknown, either for seawater or for aquaria. It involves processes that are not at equilibrium, and so are difficult to understand and predict. Even more daunting is the fact that the chemical species that control ORP in one aquarium might not even be the same chemicals that control ORP in another aquarium, or in natural seawater.
Guys the rest of the article can be found here:
http://www.reefkeeping.com/issues/2003-12/rhf/feature/index.php