Dakota9;411653 wrote: Jeremy wrote; </em>Corals calcium structures is "protected" by the living tissue of the coral, until the coral is dead, where is can be "re-used". Mollusk shell, on the contrary, is exposed to NSW condition in life and death. What enables it to freely dissolve after death, while maintining, and depositing calcium while alive?
Didn't you just answer your own question? Coral strutures were ment to last indefinately (1000's of years) and probably have a different stuture that keeps them intact, which for use as a buffering substrate, would make cc counterproductive. Shell on the other hand is quite temporary in comparison, it would be meant to breakdown relatively much faster (but still quite slow as my original shell substrate lasted well over 15 years until the folks I sold the tank to decided they liked sand better). Breaking down faster and more easily means that it has the ability to buffer water better by more readily leaching calcium, mag and carbonates into the water.
The particular article that I'm looking for states that cc starts actively buffering in a PH at or near the range of 7.7, while shell starts actively buffering at or about a PH of 7.95. If this is true (as my above statement would suggest) the use of shell would definately be beneficial as a substrate. I just have to find the article, which was actually one of several, but by far the most comprehensive.