replacing my crushed argonite gravel with sand, not sure what/how much to get

Not sure if one is better than the other it might be a matter of opinion. As far as how deep, it would depend on if you are keeping or gunna keep fish that bury themselves. I think so someone correct me if I'm wrong.
 
I would go with this sand for the bed..

http://www.marinedepot.com/ps_ViewItem~idProduct~CS0930.html

The depth is alot down to personal preference unless you want a deep sand, which is about 6 inches..For me, 2 to 3 inches is good. Also, it depends if you have/want any sand burrowing fish in the tank where a deepish sand bed is needed..

Niko
 
That looks like nice stuff but shipping to NZ is about 120US, way too out of my range..
 
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