Sand substrate for malawis

I was wondering what sort of sandy substrate would be good for peacock malawis? Aulonocara.. if you know the brand name that would be awesome. At the moment they just have a sort of gravel with crushed shells etc possibly to maintain the alkalinity. Because I heard they like to sift through sand as part of their hunting behaviour..id like to encourage normal behaviour

 

aragonite or any coral sand will do. will also help to buffer your ph levels as malawies prefers a higher ph.

 

Arogonite is the best. No PH buffers needed only some cichlid salt

 

Ok cool, I think I already have coral sand, but it has rather thick pieces in it. I wasnt sure if it was the correct sand. Ill have a look at argonite.