DSB questions

[Aleph]

Hi, I'm thinking about setting a new tank and I wanted to have some info about setting up a DSB...I have some questions:

1) What is the difference, besides the obvious one regarding sizes, between setting up a DSB in the tank and setting it up in the sump?

2) Many people build a support for the live rocks so that they don't press on the sand, to avoid anaerobic zones and consequent build-up of toxic stuff...is it really necessary and if it is, any advice on how to build this support?

3) About the size of the sand grains, some say sugar size, other say to mix finer grains with bigger grains...judging merely on a effective surface basis I would choose the smallest size available but maybe there are other factors I am missing...are there?

4) I read height should be between 4" and 6"...correct?

Thank you in advance for your help!

 

[Opcn]

1)Height on a tank is the most expensive dimension to grow in, a thicker sand bed means that you need thicker glass to get the same swimming space. In addition to that a sand bed doesn't need much light, and light may cause algae growth in the bed against the glass. Many people don't like to look at that so they don't want the bed in the light.

2)in your display tank you have lots of rock that you can topple if you aren't careful, if the sand is shifted by currents (which are often higher in display tanks) or critters you don't want your rockwork tumbling down through the glass.

3)Much of the work of a DSB is done by microaerophiles, bacteria that like just a little O2. If you use a mixture of sand grain sizes you create disuniformity in the gap sizes and effectively increase the number of microaerobic pockets in which then can do their work.

4) At a minimum yes,

 

[Aleph]

Ok, great, thank you!

 

[Aleph]

Ok, another question...what is the ideal range of grain sizes I should use? I read somewhere that it should be between 0.1 and 1 mm, is it correct?