Hi Beeba,
Its like this, its not just sand... its between DSB, Sand with Plenum and Barebottom...
DSB - Deep Sand Bed... at least 4 or more inches of sand. Very fine sand. Not the crushed coral type. You also need a lot of sand critters. A lot of people jump to this approach several years ago and a lot of people swear the its working like a charm... And a lot of people also said that it is not working...
This is a highly debated subject and very sensitive too... so read read and read.... here is the link http://www.thepsas.org/phpbb2/viewtopic.php?t=37
PLENUM SYSTEM.... its like DSB but you have a space below the sand to facilitate bacterial colonization to help filter your water biologically. I cannot elaborate more because i dont have experience on this
maybe you can read some more on this here... www.garf.org
BAREBOTTOM ... its being used for a very very long time.... very popular in Europe. You just remove these detritus via siphon every time you do water change. You can also do research on "BERLIN SYSTEM"
A lot of people came from Berlin then switched to DSB and went back to Berlin.... I for one is one of them.... why? I cannot elaborate on that except that its more simple for me to maintain....
and the other approach is a mix... a barebottom system with half inch or and inch of sand. Why? because of aesthetics.... they don want the look of a barebottom.