Coral sand is getting hard to come by in Australia and as it is taken from near coral reefs, environmentally friendly alternatives should be sought. One such alternative is crushed marble. Marble is the metamorphic form of limestone which is calcium carbonate, the relics of coral reefs gone by. It is available it various sizes from ultra fine - known as "pool dust" - up to sizes that can be used in calcium carbonate reactors.
One source for crushed marble in Sydney is:
The prices I paid (in 2001) per 25 kg bag are as follows:
Last updated: 28 August 2009