Remote DSB for my 330g, few questions.

[Jeff000]

My 330g tank is almost ready to fill. It has a 220g sump. After rocks and water level in the sump, I figure about 400g of water.

I want to do a remote deep sand bed.
I can do up to 36 long by 12 wide, by however deep I need.
Is that enough for my water volume?
How deep should it be?
Is there a GPH flow that should be going through it?
Sugar fine sand?

Tank will be dark, and I can put what ever sized bulk heads into it.

Thanks in advance.