what sand for a deep sand bed

[ethank77]

I am building my sump for my 125 reef. I have designated a section for a deep sand bed and macro alge. this section is about 12" by 18" by 13" I am hoping to put a 6 to7" sand bed with cheto ubove it in that section but am not sure what type of sand works best for a deep sand bed.

[Nereaga]

Sugar sized sand.... very fine sand to trap bacteria deep within.

[mg426]

Oolitic.