yet another question

[thewizzrd]

Why is it that sw tanks need specialty substarte as opposed to the rock that is used in fw aquariums. I know the benifits of live sand and everything but I was just wondering the major differences.
Also, even if you put dead coral and such in the sw aquarium, eventually it will become live correct?

 

[jimi]

Being the ph of saltwater is high, crushed coral in any form helps to buffer the water and help keep it high. Many freshwater substrates cant do this and may contain metals which could be deadly in saltwater.