When I was seting up my tank I found this thread.
http://www.reefcentral.com/vbulletin...002/01/3/56925

It is one of the threads that aided in my choice of sand bed. I also think you need to have about 1/3 aragonite.

I just want to post this as a comment. It is just something interesting that happened when I scooped out some of the substrate in my tank, and replaced it with glass beads.
http://members.shaw.ca/rcipema/sand.jpg
It might be Diatoms, or Cyano, but I lean toward Diatoms. Remember this is totally inert glass beads. I would stir it up, but as you might notice the Fighting Conch likes it.

Sure looks like diatoms to me, too. IMHO/FWIW of course...

Not related to the diatom thing, (and not a criticism, just an observation) but I can see one difference already....light is penetrating into deeper depths of the sandbed than it would with aragonite.

Mitch

Sitting right in front, I am not sure. The problem being that outside light is affecting it. However, it does stand to reason, because the stuff is translucent. Under 20x magnification it just looks like beads if glass. I don't really know if I personally would like it by itself. In my 20 the bottom inch is Aragonite, and pool filter sand. The tank in the picture just has two small pockets of it. :wink:

Bob, have you tried mixing it up? I know you can;t now but I wonder if they different types would stay mixed..

Steve

No problem Steve. In the interest of good scientific methodology, I will mix the part that has no diatoms. I don't want to steal the Conch's food after all. :D

Actually I just did that. I see no reason why it would not stay mixed.

I have a layer of Oolite and crushed coral along with large coral pieces over my glass shot peen.

The Oolite was live sand, the crushed coral was put there to prevent any wash from my powerheads, and the coral pieces were added to give the pods some place to hide.

A proper mixture of shot peen will supply a silt like texture that is required in a DSB - as prescribed by Dr. Ron.

I don't think it will stay mixed because the aragonite will eventually dissolve. The glass beads won't.

Mitch

Possibly a good point :wink: , but I use local water, and do not expect to live another 100 years or so waiting for it to dissolve. To temper that remark, I have had an Aragonite sandbed for the past three years, and it is the same depth it was when I put it in. :D :D