What is the primary purpose of Magnesium?

[Sooners]

In a nutshell, what is the primary purpose, or benefit, of having magnesium kept at the 'right' level? In looking at the article below, as a layman I seem to construe it to mean that magnesium helps one keep the water saturated (super?) with calcium and carbonate?



http://reefkeeping.com/issues/2006-06/rhf/index.php

[rhoptowit]

what i get is magnesium helps to keep the water saturated with calcium and carbonate by helping to prevent the precipitation of calcium. kept at the right levels magnesium would act as a buffer for precipitation from occurring, at lower levels calcium and carbonate will precipitate quicker.

[tmz]

Yes , magnesium discourages calcium carbonate preciptitation and helps keep solid alkalinity and calcium levels. Perhaps even more importantly it is used by calcifying organisms such as coraline and corals,etc, along with calcium and carbonate/bicarboante.

[HighlandReefer]

This article written by Randy goes into more details:

Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm

[2006]

Was Randy's article dated 2003, instrumental in getting hobbyist to test and dose Mg? The last time I was in the hobby was 2000 and I don't remember reefers being concerned with it then. He does say that three companies had Mg supplements on the market at the time he wrote the article.

Just looking for a little historical perpective. I am amazed how much things have changed in our hobby over the last ten years. Especially the crazy colored and expensive corals we can get now.