Update: Mbuna Tank and Fish Pics

I have crushed coral in my Cichlid tank, works good. And buffers your PH a bit
 
The only reason I've used cc instead of some other substrate is because our water is on a softer side, cc buffers it up and keeps it stable without the need for chemical buffers.

As an alternative though (if your water is soft and needs buffering) you could have pool filter sand as your substrate and use some cc in your filter as media.
 
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