P1010162

My local reef aquarium equipment supplier told me that this is suitable as use for substrate in reef aquarium he told my it is just calcium carbonate. It looks like white sand and is quite dusty to touch. Has anyone used it and if so did it work out?

I'd be interested in knowing also. Our local supplers usually use crushed oyster shell, which can have some phosphate in it, and is much more coarse than something like aragonite sand.