A little help please!!

[hobogato]

use special grade reef sand. that is what i have in my display and on the top of my DSB in my fuge, and have no problems with sandstorms. BTW, i have a good amount of flow going across both of those sand beds. I think my tank is 25X or so per hour.

[SLAYCHILD]

Well I dont have any base LR. I just stacked what I had. If I put more sand Ill have less rock to work with. So should I move the rock?

[GaryP]

They are able to go bare bottom because they are using monster skimmers, with tons of flow, and lots of siphoning to prevent detritus buildup. Its a technology driven solution for removing nitrates. They are basically removing the waste before it degrades to form nitrate. If that is what you are interested in doing I will let one of the BB guys takes it from there.

A deep sand bed (DSB) replicates what happens in the ocean where denitrifying bacteria process the nitrates in the ocean floor. Also in the ocean you have a huge dilution factor that is not present in an aquarium, not to mention a few tons of algae to use up any nitrogen wastes.

To answer your earlier question, a plenum is a cavity you create under the sand bed to allow a place for the low oxygen denitrifying bacteria to grow. You use egg crate and screen cloth to create a barrier to the sand so that it doesn't fill in the plenum. The water percolates down to the plenum and the nitrates in it are processed into nitrogen gas.