Ok, so by this stage everyone knows that calcium carbonate is THE stuff to incorporate into your systems to buffer the ph to pretty much 7.5ish
BUT did you know that there were 3 different crystaline forms of calcium carbonate?
i'll list two.
Calcite: lime stone, most marble, sea shells, oyster shells, egg shells...........
has the desired ph effect that we want
aragonite: Corals, crushed or otherwise
...............aragonite will dissolve at a much higher ph 8+ which is why it is preferred in marine aquaria.
Here is a little cut and paste from a marine Q&A site
Quote:
................any substrate you choose is almost certain to be made of aragonite or calcite. Both are forms of calcium carbonate, but arguably aragonite is to be favored for it’s better solubility and buffering capacity in seawater (providing necessary bio-minerals, buffering pH, and supporting calcification). Aragonite can begin to dissolve, in fact, at a high pH over 8.0 (a still safe level for marine life), while calcite does not readily dissolve until the pH falls well below 8.0.
then you may not want to use it exclusively...................
